Featured Vibration Consulting Case Studies
Vibratory stress relief FEA Simulation of a welded stainless steel plate
1. FEA Simulation objective:
Vibratory stress relief simulation of a welded stainless steel plate.
2. FEA Simulation Methodology and Approach:
the steps are like quenching process by this difference that, for welding, we should define a moving heat source by 2 main ways, the first is defining within Abaqus environment itself but it is time-consuming and the second is by using DFLUX subroutine that requires a linked Abaqus with Fortran or Matlab. Our FEA Consultant did it in both cases.
The other possibility for coupled or uncoupled thermomechanical steps is available but the coupled was not correct for my simulations for some reasons.
I also used different steps for loading including dynamic implicit and explicit for the last step (dynamic loading)
3. Outcome & Conclusion
in this case the results were the same but for some reasons, Our FEA Consultant extracted stress history on specific elements additional to residual stresses and natural frequencies.
*Mesh study was performed for all of these procedures.
I will explain the details of these steps in a PDF file until the weekend.
Analytical solution Development for static & dynamic analysis of functionally graded, composite and smart structures (Beams, rectangular plates and panels).
1. FEA Simulation objective::
During my Ph.D. tenure, Our FEA Consultant work extensively in the development of the analytical solutions for static and dynamic analysis of functionally graded, composite and smart structures (Beams, rectangular plates and panels). Our FEA Consultant have developed a quadruple precision-based computer program in FORTRAN to solve these mathematical problems numerically. Simultaneously, Our FEA Consultant did finite element modeling using ABAQUS to check the accuracy and efficacy of my analytical models.
For the static case of FE model: The response of the composite and functionally graded structures is obtained for the pressure load case while the smart hybrid (piezoelectric) structures are analyzed for both pressure and potential load cases.
simultaneously, Our FEA Consultant also develop the FE model in Abaqus for modal (Free vibration) analysis of functionally graded, composite and smart structures (Beams, rectangular plates and panels).
2. FEA Simulation Methodology and Approach:
For beam: The 2D FE model is used to analyze the beam structures. The 2D plane beam, with length ‘a’ along x-direction and thickness ‘h’ along z-direction is modeled in ABAQUS using the element type CPS8R (Eight-node plane stress element with reduced integration) for elastic layers and CPS8RE (8-node biquadratic Piezoelectric plane stress elements with reduced integration) for piezo-layers with a mesh size of 50 (length)*16 (thickness). This optimum mesh size is obtained by performing a convergence study, in which different mesh sizes are considered. For functionally graded layers, the spatially graded property distribution (at different Gauss points) is implemented by employing user material subroutine (UMAT). The model is developed for static and modal analysis of functionally graded, composite and smart beam structures.
For plate or panels: Similarly, the full 3D model is used to analyze the plate structures In the 3D FE analysis, 8-noded hexahedral solid elements of type C3D20RE for piezo-layers and C3D20R for elastic layers with reduced integration are used. Similarly, for functionally graded layers, the spatial gradation of elastic property (at different Gauss points) is implemented by employing user material subroutine (UMAT). The converged FE results are obtained by discretizing the rectangular plate with a 50 (length) ×50 (width) ×18 (thickness) mesh. The model is developed for static and modal analysis of functionally graded, composite and smart plate structures. The influence of the gradation of material properties on the deflection and stresses is studied for different boundary conditions.
3. Outcome & Conclusion:
a. For functionally graded structures, It is observed that the response of the structure is influenced greatly by the extent of material gradation along the in-plane direction. It is observed that as the gradation indexes are doubled from 0.5 to 1, its effect on maximum deflection and stresses are also nearly doubled.
b. For piezoelectric structures, It is observed that the varying piezoelectric layer thickness has a significant effect on the natural frequencies of the hybrid structure. The thicker piezoelectric layers help drop the natural frequencies, while on the other hand the thin piezoelectric layers raise the fundamental frequencies thereby stabilize the structure.
c. For composite and piezoelectric structures, It is observed that the 2D and 3D FE analysis of Abaqus is failed to predict the edge effects in such structures. So, to predict the edge effect in such structure some further modifications must be required in the Abaqus algorithm.
Distributed memory parallel processing
Simcenter Femap NX Nastran Dynamically Allocated memory parallel processing (DMP) solutions can be run on a single CPU node or in Parallel across multiple Computing nodes.
When Solving the FEM Simulation
in DMP mode, Simcenter Femap Nastran spins off multiple Computational processes that Closely communicate via the CPU Message Passing Interface (MPI) Inside or across nodes.
Simcenter Femap NX Nastran offers the following Methodology for Highly distributed CPU/S olver processing:
Geometric domain partitioning
Geometric domain partitioning is available for Either static and dynamic FEM Modeling Software
The system-level Matrix are automatically partitioned and Dynamically distributed to Various MPI Workflow processes.
Hierarchic domain partitioning
Hierarchic domain partitioning is a hybrid of geometric and frequency domain Approaches .
This approach is Applied for modal FEM Analysis Software
Simulation solutions and Enables Full scalability to higher levels than could be obtained with either Analysis method individually.
Load domain partitioning
Load domain partitioning is Very Suitable when there is a large Quantity of load Scenarios in a linear static FEA Software
Simulation problem .
Instead of Only partitioning the finite element model (FEM), the Force load matrix is Dynamically partitioned among MPI load domain partitioning, which does not Require Back and Forth communication between CPU processors, and is Virtually linearly scalable.
Frequency domain partitioning
Frequency domain partitioning is Also Accessible for dynamic FEM Simulation Software
Simulation Models . The frequency range of Focus for eigenvalue Numerical computation as well as frequency response is Intelligently partitioned into Respective segments that are Allocated to different MPI processes.