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random vibration PSD moments calculation?
Hii everyone, I tried calculating PSD moments my own for damage calculation and want to compare the hyperlife tool results. I exported PSD stress vs Freq plot for an element. I used statistics in hypergraph it gave the area under curve as 5201.201 which is essentially M0, using the rectangualr integration formula given by…
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2D Acoustic Simulations Possible
Hello, I want to perform 2D acoustic simulations, only acoustic pressure as DoF and no fluid-structure interaction. Furthermore, I want to simulate an open boundary, that means I need CACINF or CACPML elements. As far as I understand their description, these elements are only available as 2D elements suitable for 3D…
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Wind fluid structure interaction
Hii everyone, I have this long pole subjected to wind loads. I want to perform fluid structure interaction between wind and the pole. The pressure regions around it and the structure response and vortex shedding too. I need a tutorial for that.
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Unable to Extract Midsurface from Hollow Pipe in HyperMesh 2025.1
Unable to Extract Midsurface from Hollow Pipe in HyperMesh 2025.1 Hi everyone, I am trying to create a midsurface for a hollow cylindrical pipe in HyperMesh 2025.1 using the Automatic Midsurface tool, but the extraction is failing. Model Details: Geometry: Hollow circular pipe/tube Uniform wall thickness Clean CAD geometry…
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How to imprint a surface mesh from a pressed assembly
I have a surface mesh on a component that is pressed against another surface. I would like to avoid creating contacts between these two parts and want the mesh to be imprinted onto the unmeshed surface. When I try this with imprint it cannot fulfill my aim as the unmeshed geometry is a CAD file. What are some workarounds…
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Is there any OptiStruct shell formulation (PSHELL, PCOMP, PCOMPG, etc.) that supports surface-locate
I'm trying to understand whether it is possible in OptiStruct to place shell-element through-thickness integration points directly on the shell surfaces, similar to how ANSYS SHELL181 uses Simpson integration through the thickness. For a standard PSHELL/CQUAD4 model in OptiStruct, the through-thickness integration points…
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How to automatically improve elements failing min size criteria
I have generated my 2D tetra shell mesh which is of relatively good quality in terms of skew, aspect ratio and jacobian. I have 99 elements that would not meet my minimum size requirements and have also selected their adjacent elements. Below is just a few of them I get an error by rebuild that a size (0.16) conflicts with…
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Stress Mapping into Meshed file
Dear Team, My customer has done some linear static analysis in abaqus, due to some policy reason he is not able to share me .odb (output) file with me. In Alternate he has shared me the meshed file (.inp) format and the corresponding results in .csv format result files consist of element ID, directional stress, Max & Min…
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Unable to export mesh support file for Flux in SimLab motor NVH example
Hello, I am following the Flux-SimLab / Flux-SimLab-OptiStruct Electric Motor NVH example. At the SimLab mesh export step, the tutorial says to select the stator tooth faces and then use: Advanced > Trials > Flux This should create the mesh support file: Mesh_SimLab_ForFlux.fem However, in my case the .fem file is not…
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How to maximize RAM usage to reduce scratch size in Optistruct.
Description: How to maximize RAM usage to reduce scratch size in Optistruct. Product/Topic Name : Optistruct 2026. ** Altair OptiStruct(TM) 2026 ** ** Advanced Engineering Analysis, Design and ** ** Optimization Software from Altair Engineering, Inc. ** ** OptiStruct includes an enhanced proprietary version of NASTRAN **…
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Pretension analysis
Hii everyone, I have this confusion. I performed pretension analysis in a bolted joint. The bolt is modelled as 1D Beam element, a 18kN Pretension force is applied. The thing is when I simulate that, the displacement and stress are 1500 mm and 1000 MPa, the components joined together by the bolt, went directly inside into…
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Moving entities from Lists to Subsystems:
Description: Hello, I have been trying to modernize a model that used lists to organize an assembly into the more modern Subsystem entity. Dragging and dropping the entities in the drop down menu works fine, However, this list has a million elements that need to be moved. I tried saving selection from that box using…
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Hyperlife weld certification results import error
Hello all, I'm getting this error lately in HyperLife for weld certification. For this specific file when I try load the Model and Results file in hyperlife weld certification, I am getting this error called " Result Import has experienced an issue - aborting process " and in the status bar I can see this " *set value :…
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How to generate a superelement with bolt preload in Optistruct?
I have tried the following steps, but encountered issues. Here are my steps: ① In the first load step, I used Non-linear static analysis for bolt preload and successfully computed the results. ② Then, I added a subsequent analysis step using a generic analysis step, referenced the corresponding card in CMSMETH, and used…
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Stress relaxation in topology optimization
Hi, Does OptiStruct apply a stress relaxation for elements of a lower density in order to avoid highly stressed elements which don´t contribute much to the structural response? This is of interest for example when stress or strain constraints are applied or if my objective is to minimize the maximum stresses. I can not…
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How does the fatigue constraint influence the topology optimization result?
Hi, I was wondering how the fatigue constraint, which can be set in the DTPL card for a topology optimization, influences the topology optimization result. In the out. file, I can tell that no sensitivities are calculated for the fatigue constraint, only a check is included. However, the final result with/without fatigue…
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Stress range visulation
Hi everyone, I want to calculate stress range in fatigue load cases. Fatigue is a cyclic stress and we have 3 layers i.e., Z1, mid and Z2. When I use range in envelope of LC1 and LC2, where LC1 and LC2 are stress cycle, the value get is range = max(Z1, mid, Z2)-min(Z1, mid, Z2). But what I want is Range 1 = max(Z1 of LC1,…
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Von mises VS Prinicpal stresses
Hii everyone, I have doubts regarding which failure theory should I use. I have some papers in which they evaluate von mises for static loads and principal stresses for fatigue load cases irrespective of material type ductile or brittle eg: SS304 I referred to some papers they say use von mises for ductile and principal…
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Why does the optimization not work properly around non-design regions?
Description: I have tried running a topology optimization, however, i sometimes get that the optimized component has strange geometries around my non-design regions. As you can see, the area around my non-design region was previously round, and became hexagonal after optimization. Reducing the minimum thickness constraint…
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error while import .h3d file in HyperMesh
I've correctly run the analysis of a model using the OptiStruct solutor and it works fine, but when I try to import the .h3d file on HyperMesh It show an "error import" (look attachment); If I try to import the same file in HyperView It crash. If I directly click on the file It correctly opens with HiperView Player and I…
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INTERNAL PROGRAMMING ERROR - OptiStruct
ㅣ'm using HyperWorks 2021.2 - OptiStruct. I've tried to run modal analysis on a .FEM file, but it doesn't work. An error occurs about 10 minutes after clicking the RUN button. The error message is: *** INTERNAL PROGRAMMING ERROR *** in file "addacol.F", at location # 59. ioerr(1) = 315340 ioerr(2) = 605304 ioerr(3) =…
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How to easily find node master
Hello everyone, I need to put a force on the node master of all these rigids. I wanted to ask if there is an easy way to find and select the node master when you have a lot of rigids. Thank you in advance!
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OptiStruct 2025.1 – Thermo-electric topology optimization with switching contact states
Hello all, I am currently working on a thermo-electric topology optimization in OptiStruct 2025.1 / HyperMesh 2025.1 and I am facing two main challenges. 1) Multiple load cases with different contactor states My optimization setup needs to include 3 load cases with different switching states of contactors (open/closed…
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Prise en compte de DOPTPRM DISCRETE | couplage FLUX - Optistruct | Optimisation topologique
Hello, I am reaching out because I am encountering an issue during my topology optimizations. To give some context, I am coupling Altair Flux with OptiStruct to perform a magneto-mechanical topology optimization. The coupling works correctly and I am able to obtain several results. However, my goal is to modify the…
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Hypermesh with Optistruct v2026 - Student license error - composite optimisation
Hello, I am trying to run a composite optimisation in Altair HyperMesh 2026 using the Optistruct solver. I get results for the first iteration, but the solver doesn't do any optimisation and stops the analysis after the license check fails. I am getting the following error. In the license file, I only have features…