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An eigenvalue of 1.0 indicates the applied load is the buckling load. It's absolutely true. I have in output numerour eigenvalue minor than 1 (numerous mode). In mine complex structure, for a single mode, I have in output numerous wave in different locations. I need to select the wave of a...

Hy I must check if a structure under applied load goes in buckling with f.e.a. nastran. I did a long time back, so I need help to remember the right way to post-process the results. The f.e.m. is very complex, I have the complete wing. The major problem that I have is to understand in the case...

I'm sizing a fitting of civil aircraft, primary structure. I've started with hand calculation, considering the fitting as a rigid body and I've compared the axial stress with Ftu and Fty (if compression) obtaining Reserve Factor Rf. Then comparing the acting shear with Fsu I obtained the...

I've to model a honeycomb structure to analyse its in NASTRAN. I'm able to model laminated composite but not to model honeycomb. I've a task. I've to use a solid 3D for the core and CQUAD4 for the fabric top/bottom facesheets. I've the mechanical property of the fabric and the core. I'm using...

Let em know the meaning of this table and in which way that table can help me to build a good fem

hi your composite is laminated, isn't it? are you using nastran? Use MAT8 card to define single lamina and PCOMP to describe the stackup

dear rb1957 the last suggestion look like good but it takes time, the model is huge ... too many fastners. I need a more easy and fast solution. I'm not interested in reading the acting load at each fastener, I'm going to use the shear flow along each fastener's row. So I'm searching for an...

dear rb1957 with the approache 1) using CBUSH everywhere you suggest to use coincident nodes, but I have modeled each part on its own middle surface (I absolutely don't want to use any offset) and so I'd use CBUSH that connect two different nodes for each joint, what do you think about the use...

I'm modelling a wing with longitudinal spar and transv ribs For the flange rib/skin bolted joint I don't know if it's better to use: 1) the CBUSH (PBUSH: K1,K2,K3,K4,K5 high and K6=0 with 3 normal to PSHELL) 2) the RBE2at each fastener location I have seen same model with solution 1 and...

ok, for the rib/spar joint i'll use COMMON nodes. for the flange rib/skin joint I don't know if it's better to use: 1) the CBUSH (PBUSH: K1,K2,K3,K4,K5 high and K6=0 with 3 normal to PSHELL) 2) the RBE2at each fastener location I have seen same model with solution 1 and same model with...

ok, for the rib/spar joint i'll use coincident nodes. for the flange rib/skin joint I don't know if it's better to use: 1) the CBUSH (PBUSH: K1,K2,K3,K4,K5 high and K6=0 with 3 normal to PSHELL) 2) the RBE2 at each fastener location I have seen same model with solution 1 and same model with...

Building the fine f.e.m. of a wing structure, I'm modelling longitudinal spars and transv. ribs using 2D elements. All the spars are continuus while the ribs are cutted, I mean each rib is composed of two or three part along chord wise. It's in the real structure as in the f.e.m.. In the real...

hi I have to model a structure in fabric. The fibers are stiched: +/- 45 and 0/90. How do I built a single fabric ply in Patran? thanks

hi in a buckling analysis (sol 105) the model is in the following unit: inch, lbf (consistent). Could you confirm (or not) that is mandatory to define the material density? Could you confirm (or not) that I have to insert the card: PARAM,WTMASS,0.00259 ? thanks

I searched in the JAR 25, in the AC 43.13-2B. I didn't find any info about misalignment.

The fitting is primary structure. It joints aileron to the wing.We are in preliminary size phase. I can't use Boeing doc. I need a generic reference. What does DER mean? The use of the misalignment depend on the type of bearing?

I didn't find any reference on the misalignment of the acting load at the joint.

I have to do a fitting analysis. In particular I'm interested in the joint analysis. The fitting has a clevis, bushings and it is connected to the lug of a second fitting with a pin. Does anyone know in which JAR/FAR I read about the misalignment? thanks

Hi I'm running a fea of a composite skin. The composite is a laminated composite with ply in 0,45,-45,90 direction. The skin is modeled with CQUAD. I've to check the strain. May I obtain the strain at each ply? Is it available in *.F06 ? thanks

Hello I'm working on the sizing of the aircraft structure in composite, I'm in the phase of preliminary load. I did a first size at Ultimate Load considering the strain check and the buckling check, all the MS>0: The post-buckling isn't allowed under Ultimate Load. Now I'm considering the Fail...