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Dear All, Sorry for this basic question. I learn in past Mc/I only applicable to principal axes. But this professor use neutral axis, which is at angle to principal axes to find max and min point, but use principal axes for stress? Here is link...

Hello All, Trying to do FBD shear loads at the side fasteners 1.20" from top. What do you think? FEM output shows 110lb there each side. Figure not exact to scale.

Dear Experts, I looking for some guidance. Recently I have complete flight loads survey data on a helicopter. But still no loads FEM. I plan build a loads FEM, any suggestions on how to build one? I can model many things, but could use some guidance. Also how to apply inertia loads or loads...

Greetings, I looking for labs in USA that can do fatigue testing to develop S-N curve for main and tail rotor components. any recommendations for labs that have experience? Thanks advance, KS.

Dear all, if any of you experts know of material SN curves for A356 T6 Al alloy, preferably public aerospace sources, and multiple Kt curves, please post link. Thank you...

Dear experts, I looking for method to calculate 1 HR and 10 HR endurance limits from the working S-N curve of a life limited component, safe life part. The limits will used to monitor flight load exceedances. Any help please? Much thanks. Kristina.

Dear Experts, I build simple part model, 3D tet elements, constraints and one load, model has gaps, so I use nonlinear static in NX nastran. I have stresses checked to be output. When model finish running, FEMAP even asks if I want to import nonlinear stress and strain, I click yes, and then I...

Dear bolt experts, I confuse about bolt preload and externally applied tension load. If a bolt is installed, I use a torque to preload joint, then there is weight applied externally, will this load add to bolt tension load or not until it is more than preload? Thank you...

Dear All, I try to find at what skin or frame or bulkhead thickness (typical CSHEAR thickness 0.016") do you start transitioning from a CSHEAR to CQUAD4? Is there a rule of thumb or formula?

Dear All, I looking for something guidance document on preparing a mass moments of inertia analysis report, that compares what changed between two different aircraft based on mass changes happened between them. Any tips or links please? Thank you much...

Dear experts, I notice tie rod end double lug fitting has two lugs, one lug has a smaller hole and other a biggger hole for two size bushings, then pin go through center or all bushing, and nut on other side to clamp tie rod end in middle. But why two different sized holes for two different...

Hello, I ask this question for composite expert. I have 8 ply all zero angle fiberglass cloth layup, complex box part. Open top, rest is a box enclosure with some areas with contours radius areas. I seeing high ply "max shear stress" in my FEM. Assume that area is at the top lip, where it is...

Dear experts, I have problem with this. I have sandwich panel, I make spread sheet with all Hoffman required values. But question are: What sign to use for stress allowable values? What sign to use for applied stresses (normal stresses)? I have some elements with signma1 value greater than...

Dear Frieds, I try doing according part 2 of section C11 in Bruhn of a fuselage skin shear panel type analysis, there is a hole and edges have rods. I have shear panel average shear stress from f06, and edge rod axial stresses also. I only use the stringer axial stress, not the hoop direction...

Dear All, I looking at the nastran output of shear panel element CSHEAR and I confused with the Shear-IJ output, where I=1..4, J=1..4 Example: So Shear-IJ, what units it has? lb/in? Also what is kick output? Thanks. Kristina. Sorry about how it looks, when I paste it it shows good format but...

Dear All, I model simple plate bending sandwich panel two types. One type laminate, one with equivalent plate using method here: https://femci.gsfc.nasa.gov/hcplate/honeycomb_pshell.html But I find equivalent plate has more deflection and stress than laminate method. What reason is it? I...