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  • Users: feajob
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  1. feajob

    Risks Associated with Machining Pre-Hardened PH13-8Mo

    Hello Everyone, I'm reaching out for your input. My background is in fatigue life assessments, not materials engineering, so I'd value your thoughts on these statements: Risks Associated with Machining Pre-Hardened PH13-8Mo: Increased Residual Stresses: Machining hardened material generates...
  2. feajob

    Fuse pin

    Hello, We need to design a fuse pin for a main landing gear. The goal is to achieve controlled shear failure to protect the aircraft. Our focus is on achieving a predictable failure in shear mode rather than tension or bending, as shear failure provides more controlled separation. To control the...
  3. feajob

    Certainty of Survival of S-N Curves

    Hi, I would like to know what is the Certainty of Survival for the S-N (stress-life) Curves presented in MMPDS? Thanks, A.
  4. feajob

    S/N curves for unnotched 7050-T7451 plate

    Hi Guys, I recently noticed that there is significant difference between the predicted life with S/N curves shown in Figures 3.7.5.2.8(b)and 3.7.5.2.8(e) in MMPDS-09. Both of them are "for unnotched 7050-T7451 plate, long transverse direction, t/4 specimen locations". The second one is giving...
  5. feajob

    Best fit S/N curves for 7050-T7451

    Hi Guys, I recently noticed that there is significant difference between the predicted life with S/N curves shown in Figures 3.7.5.2.8(b)and 3.7.5.2.8(e) in MMPDS-09. Both of them are "for unnotched 7050-T7451 plate, long transverse direction, t/4 specimen locations". The second one is giving...
  6. feajob

    S/N Curves in MMPDS-15

    Hi Guys, I noticed that on page A-7 of MMPDS-15, it is written that "S/N Curves are for a 50 percent probability of survival. We usually assume conservatively few fatigue penalization factors (such as anodizing + shot-peening, surface finish, ...). But, I would like to know if you apply another...
  7. feajob

    Margins of Safety Calculation for Compression Springs

    Hello, We usually calculate Margins of Safety for compression spring as shown below: Stress = 8 K Force Dmean / (pi*d^3) (Calculated Stress at max. operating deflection) K = (4C-1)/(4C-4) + 0.615/C (Spring Stress Correction Factor) C = Dmean / d (Spring Index) M.S. = TDS Ftu / Stress...
  8. feajob

    Stiffness of Aircraft Structure at attachment point to Landing Gears

    Hi Guys, I understood that if we have a Nastran Model of Aircraft then one way to find out stiffness of Aircraft Structure at attachment point to Landing Gears is using following cards: ASET1 123 GRID1 GRID2 ... GRIDn (to have 3 x 3 stiffness matrix) PARAM,EXTOUT,DMIGPCH I also think that we...
  9. feajob

    Abaqus Unified FEA

    Hello Guys, If you have any experience with regard to Abaqus Unified FEA, please share it with me. FYI, I previously used Abaqus software and I had relatively a good experience for solving nonlinear contact problems. Now, I am wondering what is the capability of Abaqus Unified FEA? A general...
  10. feajob

    Stress Analyses for Wheel Assembly

    Hi, I found the following paper interesting (FE-based fatigue analysis): http://web.mscsoftware.com/support/library/conf/auto99/p00599.pdf Now, I am looking for any reference for conventional stress analysis and Margin of Safety calculations of a wheel assembly (usage in landing gears of...
  11. feajob

    Rework allowance for fatigue analysis

    Hello, As per our stress methodology, we consider rework allowance for stress analysis of lugs and pins, ... But, I didn't find any reference that recommends rework allowance for fatigue analysis. I don't think that using rework allowance is recommended for fatigue analysis. Because, we...
  12. feajob

    S-Basis in MMPDS-03

    Hi, I would like to understand something about S-Basis in MMPDS-03 (because, my knowledge is limited in M & P engineering field). In order to be complaint with the FAR regulation (item 23.613), one economical method is to select materials in MMPDS that contain both A- & B- Basis allowables...
  13. feajob

    S-Basis in MMPDS-03

    Hi, I would like to understand something about S-Basis in MMPDS-03 (my knowledge is limited in M & P engineering field). In order to be complaint with the FAR regulation (item 23.613), one economical method is to select materials in MMPDS that contain both A- & B- Basis allowables that are...
  14. feajob

    Margin of Safety for Ultimate Loads with FEM

    Hello, I would like to know what is the best approach for calculating the Ultimate Margin of Safety with FEM? I know that the nonlinear FEA is a better approach, but it is not a cost-effective approach for 3D complex geometry models. Consequently, I would like to employ the linear FEM with...
  15. feajob

    Lock only specific cells and ranges in a protected worksheet 2007

    Hi, I would like to know how to enable cells to be edited while leaving only some cells locked. I could do this task in excel 2000, but I have difficulty to perform this task in excel 2007. I appreciate your help. Thanks, A.A.Y.
  16. feajob

    Nastran Punch Files for Stiffness Matrix

    Hi, I am would like to know how can I get the stiffness matrix at some specific nodes of a Nastran Finite Element Model? I believe that I should prepare a punch file with contents similar to the following lines: DMIG KAAX 0 6 2 0 363 DMIG* KAAX...
  17. feajob

    Contact Analysis with Gap Elements

    Hi, I have to perform a contact analysis between two parts as follows: 1) Pin (Male Part) 2) Socket (Female Part) I would like to know if you have any experience with Nastran Gap Elements (sol 106) If so, could you please refer me to some examples? I heard that I may save time by the above...
  18. feajob

    Gap elements for contact simulations

    Hi, I have to perform contact analysis between two parts as follows: 1) Pin (Male Part) 2) Socket (Female Part) In order to do efficiently this simulation, I would like to use Nastran gap elements with sol 106. Do you have any experience with this approach? If so, could you please refer me...
  19. feajob

    How to define an Array?

    Hi, I would like to know how can I define an Array in VB (Excel)? I tried the following commands: Dim myArray(5) As Integer myArray = Array(12,3,13,64,245,75) But, I got a compile error as follows: Can't assign to array Please let me know what is the proper way for...
  20. feajob

    Catia V5 & Nastran bdf input file

    Hi, I would like to know how can I export the mesh made with GPS inside Catia V5 as a Nastran bdf input file? I found that there is a product named GPN which belongs to the MSC.visualNastran and it complements CATIA V5 Analysis. But, we don't have this product. We have Catia V5 and MSC.Patran...

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