How to do the Bolt preload analysis using 3D bolt model and and 1D beam. Out of SOL101 and SOL400 which one is preferred for the Bolt preload analysis ?
BOLT entry is used in Nastran to model bolts. Refer QRG for BOLT syntax.
If you want to do a detailed analysis of the bolt region you will want to model the BOLT with 3D elements. For an analysis of entire structure where the results in the bolt is not the main focus you can model the bolt with 1D elements.
SOL 400 is preferred approach for bolt preload analysis. The STEP approach is useful in SOL 400 where the previous step is continuation to the next step. So normally 3 steps are used to do a bolt pre-load analysis
Step 1: Bolt preload
Step 2: Bolt lock
Step 3: external load
Sol 101 can also be used with the BOLT entry, but does not have the concept of STEP. So you will need to apply the load in one subcase.
Bolt Loads are prescribed on GRIDC to represent the pre-tension, overlap or loading of the bolt. Bolt is divided into Bottom (GB) and Top (GT) segment. The bottom part and upper part are not connected by nodes. The BOLT entry with the TOP/BOTTOM are used to connect the 2 bodies of the bolt.
How input the pretension force value.
FORCE entry with node id of GRIDC.
Same number of grid points in TOP and BOTTOM. They should be coincident but it is not
required. Users who do otherwise do so at their own risk since the current design does not consider the initial offset between them. Ideally BOLT should be modeled with HEX mesh for better results.
