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TTFN RE: Training New Hires tbuelna (Aerospace)25 Apr 06 18:19I don't think "Boeing" and "Tech Excellence" should be used in the same sentence. RE: Training New Hires 2 GregLocock (Automotive)25 Apr 06 20:34Yeah, all those 747s tumbling out of the sky. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires wes616 (Aerospace)26 Apr 06 09:22Being on the Design end of a/c engineering, I am always fascinated with things I can do to better my designs before sending them to stress (and I consider myself a perpetual stress newbie) . I'd be very much interested in reading a training "faq" here about being a stress eng. Wes C.------------------------------When they broke open molecules, they found they were only stuffed with atoms. But when they broke open atoms, they found them stuffed with explosions... RE: Training New Hires AminG (Aerospace)26 Apr 06 12:23I would be interested in seeing a FAQ for stress as well. I recall seeing a Boeing Stress manual - never had the chance of using it.As to getting tired of answering the same questions - now you know how your prof's felt and how your supervisors felt when you were at your first real job. RE: Training New Hires diamondjim (Mechanical)27 Apr 06 13:56I was the old guy on the block and trainedmany underlings. It was always amazing tome that many would come back with the samequestions rather than making a reference tothe source that I would give them the firsttime they asked. I was quick to copy thesources from the guy who trained me. Is that familiar? RE: Training New Hires GregLocock (Automotive)27 Apr 06 19:26That always annoys me. I carried a notebook around for the first 6 years after graduating, even now I usually have the latest one in my bag. Asking the same question twice is sheer bad manners. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires RPstress (Aerospace)28 Apr 06 10:01The Cranfield (UK) Introduction to Aircraft Stress Analysis was a two week course which did a pretty effective intro. I don't have my course notes any more (it was over twenty years ago)...if anyone still has the contents for them it might make a good framework for a training course. RE: Training New Hires planedr (Aerospace)29 Apr 06 23:36I am not an old timer, well I am, but not really. I find I am constantly training newbs out of great schools that don't really know that much. Design is great but try to fix a bad design and get it through stress, whether you are doing the stress or not.I find the only way to start is proved them my list of newbie references and dircect them to the photocopier. I also tell them which ones to read first. I then will help with questions as we go.Their reviews or my report to the supervisor will discuss whether they have read it (effort), whether they retained it, and whether they have chosen the correct field. RE: Training New Hires 14 crackman (Aerospace)30 Apr 06 14:33Well, next year will be my 20th in aerospace as a stress engineer and I can tell you without a doubt the days of training courses are all but over at any of the OEM. In addition, there just arent enough experienced people to go around at the OEM since they pushed many of them out of the industry during downturns and the rest into early retirement. It seems these days, the status quo is hire an army of new college grads and have them solid FEM every single CATIA drawing of a part there is, then write MS based on Von Mises. Never thought I would see the industry end up this way! In addition, it seems the OEMs really dont care anyways. They say they want to provide training but dont allocate the time. In fact, I think its ironic that the OEM spend an obscene amount of money to provide mandatory training for sexual harassment, export/import, diversity, etc, etc., etc. but cant spend a nickle for any substantial engineering courses. I have personally witnessed many good new engineers trown to the wolves without any training to end up quitting their jobs out of frustration and switching industries.Anyways, I run a consulting company and we too have had to hire a couple of new hires BUT we made darn sure to set up a process to train them and make the appropriate time available. It consists of basically the following:#1. Have them spend several weeks working real aircraft structures problems and getting familiar with all of the terminology, materials, and references (MMPDS, Bruhn, Aircraft Stress Manuals (BDM,SMM,etc.)). Above all, expect them to be able to perform FBD at a drop of a hat and understand all of the basic MS failure modes. This is the most fundamental of capabilities.#2. Assign them tasks on topical subjects which provide them experience in the various aspects of structures (ie design and detailed joint stress analysis are the basics, then, other tasks such as internal loads, post-buckled behaviour, stiffened panels, etc.)#3. Assign them increasingly more difficult problems with a focus on getting them proficient in every area.#4. Make the TIME to provide guidance and help.Anyway you look at it, it is a time consuming difficult task to train new stress engineers. BUT, we need to do it otherwise the whole industry will suffer. For anyone interested, I can email a pdf of a course MACAIR wrote twenty some years ago to train stress people. It is by no means exclusive but just a good sample of the type of problems to have new stress engineers work.Also, just as an aside. MACAIR around the late 1960's use to give a test to all new direct hires and shoppers (before all of the employment restrictions were imposed). The test consisted of about 10 difficult but good sound structural problems all of which had to be completed by hand without references. Those who did not pass, were walked out that day. The old stressers of yeasteryear sure left some big shoes to fill. Unfortunately, I am not sure the industry is up to it anymore these days.Good luck to all and hope this helps someone.James BurdAvenger Aircraft and Services RE: Training New Hires SWComposites (Aerospace)30 Apr 06 16:52Yeah, the thought that everything gets dumped into a 3D FEM without any real understanding of load paths, materials and structural failure modes is downright scary. But it won't change until the next "Comet" disaster occurs. Some of us were appalled when the Airbus VP stated that the fact that the A380 wing failed at 1.47 DLL proved the accuracy FE analysis!James-I hope you can retain the engineers that you spend the time to train.Steve RE: Training New Hires GregLocock (Automotive)30 Apr 06 20:53James, can you estimate how much (a) time for the new hires and (b) mentoring/supervision time is involved? CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires crackman (Aerospace)30 Apr 06 23:23Unfortunately we no longer have "real" engineers running aerospace companies any more and they have NO idea as to the real value of experience and the need to have engineers trained in the fundamentals. It is all too common today to see 3D FEA of intercostals and shear clips. Can no one FB a clip anymore? I really do hope the industry learns this lesson without the need for any accidents.I too hope that the young engineers who are getting mentoring appreciate it. Hopefully they will see the value of working with someone who is truly interested in helping them into the industry.As for the time to train: a) new hires - 1 year to just understand/appreciate the basics / 5 years of good work til they reach journeyman level where they can handle most stress tasks. Other more complex areas require more training such as FDT which requires about 2 to 3 years of solid training and hands on work.b) mentoring/supervising - about 20% of a 40 hour work week.Good luck all and lets hope ours is not a dying field.James RE: Training New Hires Asanga (Mechanical)1 May 06 07:31Hello all, Very interesting and useful topic. Crackman, thank you for the tips. If its not too much trouble, may I have a copy of that PDF file on the stress course emailed to me? I am about to sign up also for the correspondance course by the Lake City Publishing group (Based on the Stress Analysis Book by Jean Claude Flabel). This would be an added guide to the course I think. Thank you again for sharing your wisdom.CheersAsanga RE: Training New Hires 3 prost (Structural)1 May 06 15:42Crackman: I'd be most grateful if you sent me a stress course PDF file too. How could I obtain it? thanks RE: Training New Hires Lcubed (Structural)1 May 06 15:51Hi all,For James Burd: What is the best way to get my email address to you? I would like a copy of the Macair document.thanks RE: Training New Hires crackman (Aerospace)1 May 06 15:56If anyone is interested, just send me your email address (you can do this by going to www.avengeraircraft.com and using the Contact Us tab and email me from there) and I will post it off to you. The file is pdf format and its 4.4MB so make sure your email can handle it.James BurdAvenger Aircraft & Services RE: Training New Hires StressMan2506 (Structural)1 May 06 16:04Hi SWComposites:Firstly, the Airbus VP who "stated that the fact that the A380 wing failed at 1.47 DLL proved the accuracy FE analysis" is not at the frontline of Airbus wing stressing. Secondly, Airbus wing stressing is not solid-element FE all the way; it is nothing like that at all. A stiffness model up of plates, shells & bars is run and the stresses arising used in a multitude of computerised manual-type calculations. Maybe more judicious use of FE would have produced a better result... RE: Training New Hires crackman (Aerospace)1 May 06 20:34Just as a note, the MACAIR stress course was developed (over 20 years ago) for the USAF Air Logistic Centers to train liasion engineers in basic airframe stress analysis. Not a bad cut at it, though there are many other very good ones around.James Burd RE: Training New Hires crackman (Aerospace)2 May 06 22:11To answer a few questions, the liasion structures course that I spoke of is just that, a collection by chapter of progressively more difficult structures examples and problems. There are several of these courses that the OEMs used to put on about 20 or 30 years ago but alas no more. Lockheed used to teach a very good series of courses included a very famous one on Thin Sheet theory.The course notes basically do not have an actual document number or title or any restrictions, it is more a compilation of course work and so has not proprietary stamps or references on it since it is all derived from textbook equations. Its the type of course companies and the government used to send engineers to in order to get trained on "real" world problems right after graduating. The information in it is basically what one would get from several structures textbooks but only in a simpler and more focused manner as applicable to aircraft liasion work.Hope this clarifies some questions.James RE: Training New Hires Sparweb (Aerospace)3 May 06 02:25Crackman,I'll also contact you for a copy of that training course. The test sounds... humbling. Steven Fahey, CET RE: Training New Hires Asanga (Mechanical)3 May 06 03:27Thank you for the notes Crackman. Even if its not as detailed as Bruhn, it gives quite an insight into the background of the engineering fundementals knowledge expected of a liaison engineer, or for that matter any engineer involved with aircraft structures. The course outline for the correspondance course that I want to take (Based on Flabel's book) follows a similar pattern to Macair's.CheersAsanga RE: Training New Hires aerodog (Aeronautics)3 May 06 21:43Crackman,I would be curious to hear your opinion on the use of CATIA/FEA vs. the old hand crank method. In particular, which is the more accurate predictor of the stress levels that get recorded during static test. RE: Training New Hires crackman (Aerospace)4 May 06 00:02aerodogDepending the type of test being performed (small component to full scale) both can make good and/or bad predictions based on how they are applied. Typically though, the most direct and best way in my own opinion for large scale tests is to use some sort of FEA BUT this means a normal industry standard (or that which used to be standard in our industry) "coarse" grid airframe model built by a well experienced stress analyst who knows load path very well following standard modelling practices. NOT, some ultra fine mesh or autogenerated model (dont even think about solid elements) with every minutia modeled as seems to be the practice these days. Another good alternate method for wing boxes and even fuselage structure (as long as you account for cutout redistributions) is to use a Unit Beam method (ie Cozzone method) which was used by most OEMS for decades. In fact, most OEMs designed and built all of the 1940s to late 1960s transports with this method in various forms. Boeing used it on the 707, 727, 737, 747 (and I have heard still does for prelim design purposes). The Boeing fuselage code was named TES057 while the wing was TES170 as I recall. From the old ultimate correlation reports I have seen they did a pretty good job for the most part in predicting the values.One thing to keep in mind is that whenever you are correlating always pick very clean areas to instrument. That is to say, I have very rarely ever seen test correlations to strain gages in stress concentration areas provide good (within 10%) correlation. For instance, if you are trying to validate a wing coarse grid FEM, place your gages on basic general spar cap, stringer, or skin locations as nearly close to the NA as possible and away from any cutouts, splices or discontinuities. The best way to correlate areas with stress concentrations is to perform very localized tests and even then it is difficult to obtain very good correlation. The main point in any aircraft FEM is to correlate internal loads not necessarily detail stresses. This is typically what regulation agencies are looking for in order to gain confidence in model results.James BurdAvenger Aircraft and Services RE: Training New Hires 2 SuperStress (Aerospace)4 May 06 15:39Crackman makes an excellent point about strain gage correlations.Stress engineers tend to want to locate strain gages for the static test right on the "hot spots": areas of very high strain and very high strain gradient. Gages in these location do a lousy job of providing data for a correlation effort.The best strain gage layout for a correlation is to put gages in areas of high strain but LOW strain gradient. This way the gages are less sensitive to mislocation.The best way to validate a FEM distribution on a wing, for instance, might be to put axial gages on every stringer and spar cap on both surfaces at a single wing station, with a good number of rosettes scattered on the skins in the bays between stringer gages.Too often the engineer is asked to do a correlation without the right tools.Another sign of untrained management... asking for FEM results that are "conservative". For a given set of externally applied loads, there is exactly one solution for any given structural system. Inasmuch as the model overpredicts the load in one location, it must necessarily be underpredicting somewhere else.Maybe the engineers need to be training the management!SuperStress RE: Training New Hires aerodog (Aeronautics)4 May 06 16:48crackman/Superstress,Thanks for the good answers to my off topic question?The basis for my question is to see if the reliance on FEA is the reason why manufacturers (especially start-up business jet mfg) miss their empty weight projections so often. This might make a good topic by itself since there is great effort being expended trying to make lighter and stronger materials, avionics are certainly lighter but everyone keeps missing empty weights.aerodogjust because a process can be automated does not mean it should. RE: Training New Hires SuperStress (Aerospace)4 May 06 17:05I think the reason manufacturers miss their empty weight projections is because they are made by the Marketing department, not Engineering.SuperStress RE: Training New Hires GregLocock (Automotive)4 May 06 18:35More cynically (or even more cynically) - in order for the project to proceed it has to offer better payload etc than the competition. Therefore, in order for everyone to keep their jobs, at the start of the program it is in EVERY team meber's interests to emphasise the superior performance. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires aerodog (Aeronautics)5 May 06 07:28Greg/Super,There is inconsistency here. On one hand a lament, industry is losing the ability to do good stress work yet blaming marketing/management for not hitting empty weight targets.An outsider might assume bad stress work leads to an unsafe airplane. Bad stress also leads to a heavy airplane.Take the Eclipe airplane for instance. It sailed through static test with no failures and management is thrilled. Their press release proudly proclaimed "no detrimental permenant distortion at limit or ultimate load".Is that good stress work or extreme conservatism? If an individual sheet metal part is .063 and it could have been made from .050, then it is 25% heavier than it should be.If .050 called out where .040 would have worked out, again the part is 25% heavier.If .040 instead of .032, again a 25% weight penalty.Keep this up and you have an airframe 25% heavier than it should be and it will sail through static test. Is this good stress work?aerodogdon't just rock the boat...jump up and down on the gunnels. RE: Training New Hires prost (Structural)5 May 06 11:19Would it even be possible to design the kinds of really advanced, high performance airplanes (such as the 787 will be) without the sophisticated design and analytical tools we have now? You can cite the SR-71 as one of those really advanced airplanes that was designed and built without many of the fancy tools that we have now--I doubt the SR-71 could be built in the current budget and legal environment we have now; there'd be way too much risk for the GAO and other bean counters.The positive correlations between the test data and the analytical tools are what is allowing the 'pushing of the envelope' we are seeing now, IMO. While it may trouble me to see phrases such as "Insights from FEA" (Machine Design just had such a front cover), there is no doubt in my mind that the current tools for analyses such as CFD have enabled signficant evolution of design practices. RE: Training New Hires prost (Structural)5 May 06 11:25Trying to get back close to the original topic--Anybody out there get as disturbed as I do when some person not under your supervision (say at another company) starts asking you how to use engineering software that takes advanced knowledge and years to training to understand the results (such as FEA or fracture mechanics analysis tools) and you know from the questions that the person doesn't have a mentor and/or supervisor that is helping that person to understand? Would you feel the obligation to help the person? Forget about the cost of your time; how can a company expect a just graduated engineer understand how to use the software and interpret the results when such understanding would take years of experience to obtain? RE: Training New Hires Sparweb (Aerospace)5 May 06 11:28What ever happened to the practice of designing the airplane 15% under the required ultimate strength, and then correcting the failures once the static tests are performed? Sorry I don't have a "been there, done that" story to add to my point, it's just what I heard thru the grapevine.Back to the topic at hand: it was asked earlier, what training is required for new hires. I work in a mod/repair environment. Being expected to give on-the-spot answers about whether somebody's proposed solution is acceptable or not is common. Other times, the responsibility is upon us to create the solution. These situations require a lot of resources in your head. I find the "socratic method" works well for me: keep asking stupid questions. And, never be afraid to ask the same question again, later! Once you're more familiar with the problem at hand, you may find that you will understand the same answer better the second time around. Or, better yet, the person explaining it to you will include more info, because the process may have clarified their understanding, too. Steven Fahey, CET RE: Training New Hires SuperStress (Aerospace)5 May 06 12:07aerodog,While I don't have any special insight to the Eclipse program, I would agree that if the press release is correct, having an airplane with no detrimental permanent deformation at ultimate load is indeed overkill.Boeing would call this "growth potential", but I doubt that's what the boys in Albuquerque are after with a VLJ.Is this bad stress work? It's impossible to say without more information. Parts of the design might be driven by damage tolerance requirements more than static strength.Are heavier planes "poorly designed"? Redundant structure and alternate load paths provide added safety for occupants. Think Aloha 737.Having airplanes that are too light are "poorly designed" as well. Nobody wants to own a hanger queen that can only fly 100 hours between scheduled inspections.Airplane structure needs to be "right-sized", having just enough strength to meet certification and performance goals, while not carrying unnecessary weight in non-value-added locations. This is where good stress work comes in.I think the lament about losing the ability to do good stress work comes from the new breed of "FEM analysts" that aren't well-schooled in classic theory and analysis techniques. Allow me to quote from an AV-8 stress memo from 1990."There has been a tendency in the last decade for inexperienced people to make finite element models or for the models to be made by a 'model group'. These can be very dangerous approaches. Modelers should be experienced load path persons and must work closely with the Stress and Design people that are sizing the layouts and the parts. Finite element models cannot be a substitute for free body diagrams and load path layout work. Some hard experiences have demonstrated this."In my career I've come across these types of "FEM analysts" that couldn't free body a simple box; analysts that don't understand what shear center is; analysts that are completely ignorant as to how fasteners transfer load in a joint. Some of these same analysts are fluent only in linear static analysis, and they use it incorrectly! And these were "experienced" engineers and lead engineers! I feel sorry for the new graduates who find themselves being "mentored" by such engineers!I've witnessed failures in test due to bad modeling assumptions; neglecting cutouts, kick loads, eccentricities, etc. The test I'm thinking about failed catastrophically at 75% of LIMIT load, when we were supposed to go to ultimate load without permanent deformation. This part was deliberately "overdesigned" because schedule didn't allow for a second "test-only" unit to be built - what we were testing was supposed to be flight hardware! The responsible analyst just sat there with his mouth open... he couldn't believe what he was seeing. Worse yet, HE DIDN'T UNDERSTAND WHY IT HAPPENED.These are the engineers who scare me......SuperStress RE: Training New Hires crackman (Aerospace)5 May 06 14:44SuperstressRight on! Couldnt agree with you more. I worked for a company who recently went thru the same exact experience. They argued and argued with the certification authorities that due to their state of the art finite element modeling capabilities including linear and non-linear analysis, that no full scale ultimate test of their wing was required. Well......, the wing failed at about 137% of limit! So much for state of the art. This ended up costing them millions.In the past 20 years, I have developed several airframe FEMs and IMO here is what much of the industry has forgetten about analytical methods and particularly FEM from its original inception and use in the aircraft industry. Back in the olden days, EVERYTHING was tested and the results evaluated (that is what all of the OEM stress manuals are based on - the famous Lockheed bathtub fitting method was based on P38 and B17 wing attach fitting tests). Analysis was used only for preliminary estimates until the test could be completed. THEN, and ONLY THEN, would methods be reviewed, modified, altered in order to predict the test failure modes. Having done this and established these methods, THEN the methods could be used to help evaluate new designs without repeating the expensive testing. LESSON NUMBER ONE - ALL methods must be correlated and validated. The FAA does not accept FEM without test validation, period. IMO the industry has become far too arrogant.Now keeping this in mind, the experienced engineer knows that he must validate his method/FEM throughly at least ONCE and capture all of significant failure modes. Then, the method/FEM can be used subsequently for any new designs, mods, etc. This is the proper way to approach the issue. Most OEMs have spent millions of dollars validating their methods and have a large volume of substantiation data (even if there arent any engineers left at the OEM who know where the find the data). In fact, Boeing has a wonderful manual on exactly how to idealize airframe FEM which is based on decades of validation. Unfortunatly, the people running companies today have no clue about this. Worse yet, many management teams of upstart companies think ANY testing and/or methods development to be a complete waste of money since CATIA with FEA is the solve all solution. Worste yet, young impressionable engineers start to believe this as well because "senior management must know what they are talking about", NOT. Unfortunately for them, they end up paying thru the nose when the day they submit their mod for an STC, the FAA says the following "...thats all fine and dandy but where's your validation to test data?".....The engineers are left bugeyed and the management team disappers or better yet blames the engineers. Shortly thereafter, the company folds up and lays everyone off. No one benefits from this.One last comment then I'll get off my soap box. Many an old stress engineer always told me: "If half the design team and management arent pissed off at you, then, youre worthless to me as a stress engineer and you should call yourself one". I believe this to this day. Stress engineers must have a backbone and stand up when need be. Stress is the last defense line for a safe airframe.Good luck all.James Burd RE: Training New Hires GregLocock (Automotive)6 May 06 01:15"Would it even be possible to design the kinds of really advanced, high performance airplanes (such as the 787 will be) without the sophisticated design and analytical tools we have now? ...The positive correlations between the test data and the analytical tools are what is allowing the 'pushing of the envelope' we are seeing now, IMO. While it may trouble me to see phrases such as "Insights from FEA" (Machine Design just had such a front cover), there is no doubt in my mind that the current tools for analyses such as CFD have enabled signficant evolution of design practices. "I agree. The amount of what-if and optimisation that can be done in FEA is an important extension of the engineer's toolkit. We can also run analytical DOEs and end up with a more robust design. SparWeb (Aerospace) 5 May 06 11:28 "What ever happened to the practice of designing the airplane 15% under the required ultimate strength, and then correcting the failures once the static tests are performed? "Ah, the Colin Chapman design method! It's a bit bogus - if you truly designed to 85% then you'd have to improve EVERYTHING by 18%, so to some extent it only worked because the design process was generally conservative. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires Sparweb (Aerospace)9 May 06 15:02The Chapman that hooked up with Burt Rutan years ago? Then I stand corrected. That may go over well with ultralights, but clearly everyone here prefers to talk about transport category and large passenger aircraft. Steven Fahey, CET RE: Training New Hires GregLocock (Automotive)9 May 06 20:19No, Colin Chapman from Lotus, two apocryphal stories:A designer was working on a suspension bracket. They tested the car, and it broke. So the designer redesigned it, made it heavier, they tested it , it broke. So, he redesigns it again, made it heavier, and they test it. It doesn't break. Chapman looks over the designer's shoulder, and says " Oh, I think we'd better go back to the previous design".The ideal racing car should fall apart as it crosses the finishing line. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires SoonerMitch (Mechanical)10 May 06 20:37Systems guy here. My standard method is to give a new engineer a brand new bound engineering notebook day one. Step 1: A reasonable response given to a reasonable newbie question. Generally, guidance and directions on where to go look it up, but not answer question. Then expect them to come back with answer.Step 2: Occasional repeat offenders who are making progress are directed to look in their notebook. Repeat Step 1.Step 3: Habitual offenders are shown to the door. Small business + at will state. Generally, a 6 month window to usefulness is expected. RE: Training New Hires StressMan2506 (Structural)11 May 06 02:21FAO Greg Locock:Did the suspension component that Colin Chapman wanted to revert to undergo static or fatigue failure? Presumably the "ideal" racing car fails in fatigue as it crosses the line...Louis RE: Training New Hires Sparweb (Aerospace)12 May 06 18:08Greg Locock: The ideal racing car should fall apart as it crosses the finishing line.I thought that was GM: The ideal production vehicle should fall apart the day after its warranty expires...(Sorry, I'm too cynical, and they're too easy to kick when they're down.) Steven Fahey, CET RE: Training New Hires GregLocock (Automotive)12 May 06 21:29That's the logical outcome of the short term view in modern business. What would happen then is that the resale value would drop, so the car would be more expensive to lease from new. To pick a bad example Hyundais have created a new market, you buy one and run it into the ground over six years. It's a bad example because Hyundai in practice have improved their reliability more than anyone else, in the past few years, because with mass production improving quality is cheap and effective.In practice, of course, a car that has finished its warranty will typically be MORE reliable than it was during the warranty period. Cars are massively overdesigned in my opinion. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires crackman (Aerospace)13 May 06 14:03Just a quick word or two regarding refined designs specifically regarding aircraft. What everyone seems to forget is that you would only ever design something to "wear out" (as we do not design things to fail) at a specific time IF you never wanted to extend the design in the future. Once you tailor a design so specifically it is almost impossible to extend the design without major redesign ($$$M) costs. Also, another little thing to remember is that there are ALWAYS discrepancies which need to be addressed during manufacturing, ie MRB type repairs. If the design is too refined, you will be scrapping rather than repairing every part which has a ding, dent, scratch, short ED,etc (by the way this gets past on to customers by increases in production costs). The reasons for having "pad" on your design is to enable it to weather thru normal repairs and desirable design changes. Is anyone aware of a popular aircraft that has never had a design weight increase? Also, a bit tough to pull over to the side of the road when a part fails on an aircraft.Anyways, just my own opinions.James RE: Training New Hires GregLocock (Automotive)13 May 06 19:58"a bit tough to pull over to the side of the road when a part fails on an aircraft."Agreed, that's why the factor of safety on a skyscraper should be higher than that of a gatepost.However, isn't the dirty little secret that we pile safety factor on safety factor, generally? All with good reason, of course. That is what you exploit as the life of the product is extended. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires StressTheGame (Aeronautics)14 May 06 22:58Going back to the original question, I would recommend Practical Stress Analysis (PSA) by Jean-Claude Flabel as the best single source for what I refer to as "wisdom of the ages" assumptions or simplifications. I was lucky to attend the course Flabel gave at Boeing in 1989 and everyone considered it extremely valuable. Even if you cannot attend the course, his writing style is down to earth and allows you to see into his rationale. I have mostly worked as a Stress Analyst and had the priviledge of working with some very talented old-timers in the 747 Post-Production Group and Boeing's Airplane on the Ground crew. I have worked at Boeing Everett (12 yrs), Hawker de Havilland Australia, Hawker Pacific Australia, Civil Aviation Safety Authority, and Royal Australian Air Force. Jean-Claude's book is the prime reference source I recommend to engineers wishing to gain practical knowledge - even more than what most "practical" training courses can provide. RE: Training New Hires AminG (Aerospace)15 May 06 08:00Second the motion: The book by Jean-Claude Flabel, "Practical Stress Analysis for Design Engineers" is superb. His website is www.psa1.com. I recently ordered the book and I would highly recommend it along side of Bruhn. RE: Training New Hires jzbick (Aerospace)16 Jun 06 10:22Good comments!! Felt I should chime in - especially with James comment "I have personally witnessed many good new engineers trown to the wolves without any training to end up quitting their jobs out of frustration and switching industries."James - I'm probably one of the ones you're talking about. I came fresh out of college into the referenced company, and immediately placed in the FEA group. After switching to the stress/FDT group, it took me a long time to learn (unlearn) that detailed FEA is NOT the way to do stress analysis, it's only a tool. After much frustration of seeing what goes on in this industry (at least in one major company), it was frustrating and downright scary. Part of the reason I did indeed leave the aerospace industry.The other issue with regards to training shocked me. There was NO formal training or mentoring program set up for new hires. At least in my case, it seemed the general attitude was throw someone into a job to fill the position, without regards to their career or the quality of the aircraft produced.I sat next to incredibly talented engineers, and learned the most by listening, and asking queestions. But when I saw vice-presidents walking up to talented stress engineers and forcing them to sign-off a bad design ("make that negative margin positive - we gotta get the plane out the door"), it really made me wonder if its worth it to continue in the engineering field.I now work more in the Mechanical/IT field supporting engineers designing copiers/office equipment, and I have seen more free-body diagrams, structure/mechanics courses internally for any employee, training & mentoring than I did in aerospace. RE: Training New Hires crackman (Aerospace)6 Jul 06 17:00JasonThat must be you. Good to hear from you and congrats. You are right on about the difference in attitude towards training in the aero industry versus other industries and its only getting worse day by day.AllI appreciate everyone's interest in the liasion training course but after emailing out about 50 copies I really cannot keep up with the requests anymore. Could some of you other folks whom I sent copies to disseminate to new requests? Thanks, I have just gotten way too busy at work to keep up with all the email requests.James RE: Training New Hires prost (Structural)6 Jul 06 17:07crackman: How about I post it on my ftp site, anybody can download it? Did you ever find the answer key? You can download the stress course at _Course_for_Liasion_Engineers.pdf RE: Training New Hires liaisoneng (Aerospace)7 Jul 06 12:29As a former Liaison Engineer, now a Stress Analyst (for the past two years), I am surprised no one mentioned the Boeing Structural Repair course for Engineers. I took it later in my career, after I'd learned most of the precepts through the school of hard knocks, but I believe it would be very valuable to new graduates. It covers load path, repair sizing, fasteners, etc at a fairly high level with good example problems. While Ma Boeing charges for it, all of our new hires who had the opportunity to take it, speak very highly of it. It is relatively elementary for Liaison problems, but the advanced courses deal with compression instability (buckling and crippling), as well as durability and damage tolerance.Russ RE: Training New Hires rb1957 (Aerospace)7 Jul 06 12:52after many years i've come to the conclusion that courses are best left to horses. the most i've ever gotten was a few ideas about things, which i then followed up on my own.one company i worked with started a training internship for new grads, trying to fill the gapping void between school (today) and the practical needs of the work place, where they went through several departments (hopefully figuring out how the plane was put together, at least finding people in these various departments to go to later) and they also went through the rivet school, learning how to buck rivets. i always thought that was a valuable lesson.as for interview testing, what people here are starting calling "the inquisition", its depressing how few grads can solve a simply supported beam, let alone stress a bracket.TTFN RE: Training New Hires crackman (Aerospace)8 Jul 06 00:26Thanks prost for posting the liasion course notes, greatly appreciated.In addition to the structural repair course, Boeing has some great training books which they use in their stress, fatigue and DTA courses. They give a very good review of structural analysis for all components of the airplane and then get into specific details of analysis. I believe it used to be contained in two notebook binders if I remember correctly.I do agree as well that training must be both in the classroom and hands on to get the most out of it. Much of this relies on your boss and his willingness to expose you to the various aspects of being a stress engineer. It is unfortunate that most new grads have very little to no experience with real world problems. Heck, most dont even know what Mil-hndbk-5 is. In my own opinion, this has alot to do with the fact that professors today have little to zero experience in industry. In the old days, most professors came from industry and valued exposing their students to real world problems and not just ivory tower projects to get them funding for the next several years. I have approached universities in the past to have them do structural testing for me only to be turned away because they were not considered cutting edge.James RE: Training New Hires Sparweb (Aerospace)14 Jul 06 14:39This thread has become much more meaningful for me. I am 6 weeks into supervising a summer student. I've discovered some surprising attitudes that somehow get picked up from university M.E. classes, that I'll pass on, if it's helpful:Airplanes must be made of carbon fibre,Airplanes must be designed with highly detailed 3-d models,What's with all these dusty old books?We've overcome some of these things by working on the basics - how to draw good drawings, what materials to choose, looking through fastener catalogues. While re-stocking some shelves in the shop, he had a 4130 tube in his hand and asked "this is steel?" Yes... "But it's so light!" Of course... "How can steel be so light?" A lesson was learned.University courses really don't give students much contact with materials, so a teacher telling them that graphite is the most structurally efficient material leads them down a rather costly path. Students then get themselves into design competitions, and lord help them, these 20 year-olds are sawing and grinding CFRP projects with no masks on!The foregoing discussion prepared me a little for the task, so thanks to all. When it's time, I'll bring out the course notes (thanks again Crackman). Steven Fahey, CET RE: Training New Hires compositestress (Aerospace)16 Jul 06 19:20This is not a complaint !!!!You can download the stress course at _Course_for_Liasion_Engineers.pdfDoes anyone have lesson 14 and 15. The pdf above stops at page 14-2.Many thanks RE: Training New Hires prost (Structural)18 Jul 06 10:17compositestress: durn, I didn't even notice that. I was going through the PDF, didn't get to the end yet. The PDF unfortunately is how I received it. RE: Training New Hires prost (Structural)18 Jul 06 15:23compositestress:The PDF I put on my ftp site had pages in wrong order; looks to me as if they are all there, just mixed up. RE: Training New Hires crackman (Aerospace)20 Jul 06 11:10AllJust a note to say that I am not ignoring peoples request for the liasion course notes but hoping rather that people will see the links that prost and compositestress kindly provided for copies of the notes.Sorry but I really just dont have the time to email everyone back. Also, this is to prost or compositestress, I do have the answer key. When I get a chance to scan it in, I can email it to either or both of you so you can post it. But, you should probably make people send you a copy of their work first so they can demonstrate they actually worked the problems, ha ha. Would be interesting to see the grade distribution. Anyways, will post when they are available.James RE: Training New Hires compositestress (Aerospace)13 Sep 06 16:08Crackman Did you get a chance to scan the answer key?Also, what is MAC 339? CS RE: Training New Hires fbdandloadpath (Mechanical)15 Sep 06 23:00CS,MAC 339 is McDonnell Aircraft Company Report 339 - a strength (stress/structures) manual from the days in St. Louis before Boeing or even Douglas. It came from back when they called themselves Mac-Air.FBDANDLOADPATH RE: Training New Hires plasgears (Mechanical)26 Sep 06 11:30At GE engines we had a staff of Phd engineers who published monographs that helped the newbie learn fundamentals about various structures like flanges, mounts, frames and other space structures, vibrations of stators and blades, etc.One helpful publication was a compilation of historical lessons learned. It helped one get over the stupid and inexperienced phase. I remember the evolution of nozzle actuator mounts. It went from the 'suitcase handle' thru the 'shearplate and floating pin' to the current thrust tube and ring arrangement. (We killed more German pilots in the F104 program than during some major air battles over Europe. The exhaust nozzles kept separating from the engine.) RE: Training New Hires plasgears (Mechanical)2 Oct 06 14:01crackman,I presume you are into fracture analysis, among other things. My early exposure to fracture analysis was from an attached MME who specialized in fracture. I used his work in my jet engine components, and it got the attention of Wright Field. They ran with it and used it to get fracture of major components under control.(circa 1975) RE: Training New Hires crackman (Aerospace)26 Oct 06 09:38Compositestress / ProstI finally have the solutions for each chapter of the Liasion Course scanned in, just email me separately (at my personal email address) and I will forward it to both of you so you guys can post it on your sites. There's no way I can keep up with other individual requests.By the way, as I was digging through my references, another good reference for basic structures training is the book entitled "Aircraft Structural Analysis" by the Martin Aircraft Company, 1947. Its a practical reference on aircraft structural analysis with numerous problems to work out which are realistic. RE: Training New Hires StressTheGame (Aeronautics)1 Nov 06 16:51Crackman,thanks for scanning the solutions! Compositestress / Prost,Thanks in advance for the upcoming post! RE: Training New Hires prost (Structural)2 Nov 06 13:35For those of you looking for the solutions to the aircraft structures problems contained in the crackman document, Stress_Course_for_Liasion_Engineers.pdf, you can now access it after sending me $19.99 first...no wait, just kidding! You can download it at The solution document is titled Aircraft_Structures_for_Engineers___Solutions.pdf. Crackman requests that you try to get it from this ftp site first, and if you have trouble down, come back to this thread and tell us you can't download it. RE: Training New Hires Asanga (Mechanical)2 Nov 06 14:38Crackman, Prost and Composite Stress, Thanks for the efforts in putting the solutions out there.Crackman, can't believe that you old school blokes had solution manuals ("Solution manuals? We don't need no darn solution manuals, those are for sissies. Back in my day we ground out the problem on a slide rule, and KNEW it was right!" j/k much respect for ya!) RE: Training New Hires StressTheGame (Aeronautics)3 Nov 06 05:41Prost,thanks!! - worked like a charm! RE: Training New Hires jonnycowboy (Mechanical)5 Nov 06 19:22Thanks for the solutions, the PDF works great :) RE: Training New Hires Sparweb (Aerospace)7 Nov 06 14:49Thanks for preparing and posting the solutions. Steven Fahey, CET RE: Training New Hires Dave1501 (Aeronautics)15 Nov 06 16:55crackman,I stumbled across this website and your 30 April 2006 entry regarding training new stress engineers. I am new to the aircraft structuaral analysis scene. Meanwhile, my current employer treats its employees well but there is a vacuum of in-depth, industry specific technical training. And yes, it is frustrating, especially for someone who background is mechanical engineering. In your 30 April 2006 entry, you offered to email anyone a PDF file of a training class from MACAIR. ("For anyone interested, I can email a pdf of a course MACAIR wrote twenty some years ago to train stress people.") I will take your offer and a copy of that class and any other information regarding training, text books, and any references that you may be willing to offer. Any suggestions regarding the best way to exchange contact information would be appreciated. Thanks.Dave RE: Training New Hires prost (Structural)15 Nov 06 19:07Dave1501 and anyone else who is interested:crackman graciously provided me with two PDFs--the questions, and the solutions, which crackman allowed me to put on my companies ftp site. Due to the overwhelming volume of requests, crackman requests that you get those two PDFs there, rather than ask for direct email. Here's the site: currently there are two files there, download them both. It's all free, thanks to crackman and my company providing a tiny bit of space on a server. Let me know if you can't download them for some reason. RE: Training New Hires Dave1501 (Aeronautics)16 Nov 06 10:25Prost,Thanks for your efforts but I was able to access the website. When I clicked on the provided link, my PC responded with a dialogue box titled "FTP Folder Error". The dialogue box stated "Windows unable to access this folder." Any suggestions?Dave RE: Training New Hires prost (Structural)16 Nov 06 11:26Hmm. I assume you mean you were "unable" to access the ftp site. I just tried it, 10:15 am Central time, twice, once on my IE, the other time with my Firefox. Worked both times. Did you mistype something? I tried it both ways; typing in the address, and just clicking on the link above. Maybe there was a hangup in the server just when you were trying to do it. Please try again, and come back to this thread if you still have problems. We'll stick it on our company's commercial website temporarily and you can download from there. RE: Training New Hires prost (Structural)16 Nov 06 17:21Something changed in our ftp site administration without our knowing. This might work better: try downloading both documents there. RE: Training New Hires prost (Structural)16 Nov 06 17:42ARGH! This ftp appears to be erratic. We put the two files in a more dependable location You'll see two files there below the Parent Directory. Right click on a file, a menu pops up, use Save Link As option, and put the file on your PC wherever you like.I apologize for the inconvenience and the screwiness of our ftp. It's never screwed up for me before; are there sun spots today? RE: Training New Hires Dave1501 (Aeronautics)17 Nov 06 00:10Prost,I was able to open the ftp site when I got home. Love the typed pages... all 500+ of them. I have lots of work to do! Thanks.-Dave RE: Training New Hires prost (Structural)21 Nov 06 10:25OK, I have put the notes and the solutions in 3 places: Depending on the phase of the moon or some other arbitrary event, either or both or neither of the first two works. As far as I know, the last one always works. If you are still cannot get these two documents, please let me know and we'll figure out some other way to get those documents to you. RE: Training New Hires Asanga (Mechanical)21 Nov 06 14:26Guys, Seems like an asinine question (not that that stopped me before), but what are your views on an old dog learning new tricks? Can someone from a design background (or any other such as Quality) actually change positions and go into Stress and make it? More importantly, would any sane company manager consider this as a worthy investment over training a newbie? As for me, I want to learn about stress analysis simply to increase my understanding of Aero Structures, but I couldn't help wondering. RE: Training New Hires GregLocock (Automotive)21 Nov 06 17:27From what I remember of that training course, if you can understand it, and the theory behind it, you should be able to walk into a stress job.You'll be far better prepared than most grads these days. CheersGreg LocockPlease see FAQ731-376 for tips on how to make the best use of Eng-Tips. RE: Training New Hires Asanga (Mechanical)25 Nov 06 12:08Cheers Greg thanks for the response.Asanga RE: Training New Hires Andries (Aeronautics)28 Nov 06 03:14Hi Asanga,The big thing is a willingness to learn. Your design background should actually help since you will already have an understanding of materials, fastening systems, loading actions etc. that you would need when stressing.RegardsAndries RE: Training New Hires pseudo5678 (Aeronautics)14 Dec 06 03:14Sorry to resurrect an old thread, Hopefully this will get noticed.I really appreciate the pdf being made available. I was able to ftp OK, but the solutions file is no longer in ftp.apesolutions.com/pub, the http link is 403'ed, and ftp.apesolutions.com/anonftp/pub doesn't exist.Any chance that the soultions file could be put back on the ftp site?Thanks,Jeffrey RE: Training New Hires prost (Structural)14 Dec 06 10:40I am very sorry you had so much trouble Jeffrey. We had one of those unscheduled, uninformed (meaning they didn't tell us about it) decisions by our webhosting company that goofed up our blah/pub site. Try one of these 3 sites, You're looking for these 2 files, though you can download anything else there if you like.Stress_Course_for_Liasion_Engineers.pdfAircraft_Structures_for_Engineers___Solutions.pdfIf none of those 4 locations works, email me at drfeaNOSPAMYOUSCUM@yahoo.com (removing the obvious letters! lol). Sorry about the problems, it was really not under our control (even our company website has been FUBAR for a week. It's darn frustrating!). RE: Training New Hires prost (Structural)14 Dec 06 11:32pseudo5678: note the "YOUSCUM" in my email address in my latest posting was not referring to you or anyone else in this forum! RE: Training New Hires pseudo5678 (Aeronautics)14 Dec 06 16:27I was able to get the file. Thanks very much for hosting it, and thanks to the original contributor. RE: Training New Hires prost (Structural)9 Jan 07 16:26OK, I have a new, permanent location for the Stress Course for Liaison Engineers and solution manual PDF files: Stress_Course_for_Liasion_Engineers.pdfAircraft_Structures_for_Engineers___Solutions.pdfGo to this HTTP location right click on the desired file(s), copy to your computer where you like. If you double click on either of the files, ADOBE Reader opens up so you can see the file directly.Sorry for the inconvenience. You can still send me email and I'll send you the two files. RE: Training New Hires crackman (Aerospace)12 Jan 07 22:33Just a quick note to all as I keep getting requests, please use prosts site.Also, by the way, I just want to clear up one misunderstanding about the notes. These course notes are NOT a MACAIR document, I mispoke in the very first email. The course notes are simply a set of old informal clasroom textbook training notes which air force liasion stress engineers were given and were not classified or proprietary material and were not official in any manner shape or form. They were just plain textbook type problems and solutions for structures related work which were given as part of training for liasion engineers. So, there is no reference document number, title, or code related to it. Its simply unofficial course notes no different than those you would have had in any aircraft structures book and which you could obtain from any number of good books such as Bruhn. The only benefit is that the problems are made to relate to practical problems. Hope that answers everyones questions. googletag.cmd.push(function() { googletag.display('div-gpt-ad-1406030293255-2'); }); Red Flag This PostPlease let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.CancelRed Flag SubmittedThank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. 2b1af7f3a8