Hi, I have two conducted two random vibration testing with the same profile but different duration.
In Random Vibration, since it is linear analysis, no time parameter is needed... I would like to calculate the vibration energy based on duration and Grms.
Is the vibration energy formula...
Hi, I would like to know if the duration is different for the same random vibration test profile, would the energy still the same?
For example, if the part break under the profile below for 60sec, would this failure occurs to be expected for the same profile for 20sec?
Are we able to capture...
Hello`
I am designing an assembly trolley and determining allowable deflection of the plate as shown in red arrow in the picture (for reference) below.
May I know if there is standard for the allowable deflection? I understand for some beams design, there are rule of L/360 for instance. What...
During modeling assembly, always assume subsystems as point mass with MOI if the subsystem is large...
But why don't we model the subsystem in a simplified model (shell models)?
When we want to check for coupling issue, we then better to use reduced model for subsystems to be integrated with...
Hi, I always concern about inter-rivet buckling if the spacing is too large...
What about insert in honeycomb panel if the spacing between insert is too large? Is there a general rule that we can use, or we just calculate the buckling based on the alu sheet?
Hi, I wonder if we need to multiply the limit load with all the factors at qualification test level.
Static load = Limit Load x Design Factor X Yield Design Factor X Qualification Test Factor?
If I am extracting the bolt forces from the FEM model, should I also consider fitting factor as well...
Hi, I would like to ask if I should expect to see the frequency response same as PSD input for random vibration when the subject is stiff enough >500Hz?
I create a plate and run a modal analysis to get 700Hz+++
Then I run a PSD profile as below...
I thought I would get the output same as...
Hi, I extracted PSD output from ANSYS with 2.5% and 3% damping ratio. I would like to check if the envelope I make is reasonable?
I notice the amplitude of 2.5% is very high, up to 5 G2/Hz. If the envelope covers the peak, does the shaker able to take so high energy?
PSD Input is as below. The...
Hi, just to check the Grms for electronic equipment. Why is it smaller component (30gram) can take up to 15Grms,heavier component (400 gram) can only take 8Grms?
Hello, want to check in airframe assembly such as fuselage modeling, how do you handle the connection between the skin, frame or longeron? Just to merge them or using rigid element connector?
If we merge the frame to the skin, are we still model all parts as midsurface? There will be gap...
Hi, I am looking for any frequency response requirement for subsystem from Ecss standard. I tried to search through ECSS-E-HB-32-26A but I could not find any.
Does anyone know we can find the frequency responses requirement from Ecss? Thank you!
I would like to model 2D elements for orthotropic material properties but the properties I set for Z direction is assumed as very small value as I do not have test data.
Should I use 3D in model type or 2D with plane stress? I am not sure what error do I have when I set it to plane stress
I am using CLT to calculate the modulus for a whole stack up. I got a poisson's ratio 0.7 for 4 plies of +/-45 deg.
When I use this data in FEM with orthotropic material, there is an error if the possion's ratio more than 0.6. May I know why?
Would higher poisson's ratio result in higher...
Hi, I doubt at the properties below. Based on Toray website, T800H is fabric but the table below shows the modulus more like unidirectional.
What do you think?
Hi, I would like to estimate the ply density of a wet layup.
I have fiber SGM, ply thickness, resin content. Is the formula below legit to use for calculating resin gram?
Once I have the resin gram, I will add them up with fiber gram and divide by the ply thickness from measurement to predict...
