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  1. DJL Eng

    Instruction for managing new Thread Notifications and Accessing your watched forums

    +1 for LittleInch's post. Please tell me our archived posts have been saved...
  2. DJL Eng

    Perpendicularity Stack-up

    Can perpendicularity tolerances stack-up? See the attached picture for an illustration. I could not find the answer on this site or elsewhere. I am a GD&T noob so I apologize if this is a silly inquiry. Assume compliance with ASME...
  3. DJL Eng

    Stiffness Matrix/ Solving for Displacements Problem

    I appreciate you doing/showing the work IDS! I agree that there should be a reaction at the wall. I guess I also failed to realize we could remove rows/columns once we know nodal constraints. All that said, I might just punt this book to the side and use a different reference to learn FEA...
  4. DJL Eng

    Stiffness Matrix/ Solving for Displacements Problem

    Sorry for the lack of detail. Here are the previous pages:
  5. DJL Eng

    Stiffness Matrix/ Solving for Displacements Problem

    Thanks for the reply rb! That's a clear explanation. I guess I am still struggling on the math part. If I multiply out the first equation, I get 1*10^8*(4.546*0 - 4.546*U_2 + 0*U_3 + 0*U_4) = 0 or U_2=0. Did I completely flub that one? Intuitively, my answer does not make sense because...
  6. DJL Eng

    Stiffness Matrix/ Solving for Displacements Problem

    I apologize in advance since this might be more of a math problem. I'm trying to learn FEA and I'm going through the first example problem from the "Practical Stress Analysis with Finite Elements" book by Bryan Mac Donald. Here is the problem: I don't get how we can just take the first line/...
  7. DJL Eng

    Member slippage/ bolts in bearing?

    Again, many thanks for this discussion, y'all. I feel like I have more than enough information to go forward.   @Tmoose Currently the design calls for 12 bolts/ nuts and through holes. We have not yet machined the bolt pattern in the structure. @SWComposites Lol, I'm pretty surprised at...
  8. DJL Eng

    Member slippage/ bolts in bearing?

    @EdStainless Ah, so I guess for the initial slip I should figure out how many bolts come into shear based off of GD&T of bolts and members. @desertfox I have to investigate the effect in the differences of the test assembly materials and actual assembly materials.
  9. DJL Eng

    Member slippage/ bolts in bearing?

    Thank you for the replies everyone. There is only one other mechanical engineer to discuss this with at my job, so it's really nice to receive these different inputs. @desertfox I am not sure what you mean by the "original device", but I assume you are talking about the "component" in my...
  10. DJL Eng

    Member slippage/ bolts in bearing?

    @desertfox For coefficient of friction, I used the worst-case values from my Machinery Handbook. However, I see your point. Friction values can vary wildly and without any testing or historical data I won't actually know the coefficient of friction. Lastly, the component is an existing device...
  11. DJL Eng

    Member slippage/ bolts in bearing?

    Thanks for that link; it's a good read. The shock load is not cyclical. Currently the mounting plate does not use alignment aides. It still seems that if I apply a preload to apply an adequate counteracting friction, then the 'critical slip distance' wouldn't be achieved.
  12. DJL Eng

    Member slippage/ bolts in bearing?

    I am trying to determine bolt stresses from a resulting shock load. A component is bolted to a mounting plate and the mounting plate is bolted to a fixed structure (see attached sketch). The system sees some acceleration due to shock. We cannot bolt the component directly to the structure...
  13. DJL Eng

    Shock Requirement Interpretation

    @geesaman.d Thanks for the reply! Based on the size, shape, and mounting method the acceleration could be inferred. I'm digging through some manuals at the moment to see if I can tie a requirement to this drawing to help me make some conclusions.
  14. DJL Eng

    Shock Requirement Interpretation

    I hope I've found the correct forum to post this. I was given a job assignment to evaluate a component under shock load. I am completely new to this type of analysis and was hoping to get some clarity on a note I found on a related drawing. The note says: "Maximum force transmitted during...

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