Welcome to the LS-DYNA Product Space

<p>大家好 我已经创建了风管和四个支架 并给他们定义了截面和材料 下一步我应该干什么 可以告诉我具体要使用什么关键字 我想分析在风管重量的情况下四个支架的受力</p>

<p>需要物体承重受力分析 静力学分析的案例，有没有好心人告诉我哪里有</p>

<p>lspp如何创建空心长方体网格，长方体壁厚是一毫米</p>

<p>i cant understand why my airbag pressure decline to zero in 20ms .The airbag was deployed at 45 ms , i implemented it by defining a delay ,as show in under figure , my airbag's keyword is *AIRBAG_HYBRID .I removed all the components except the airbag, and its pressure stopped dropping. I would greatly appreciate your help.</p>

<p>Hi,</p><p>I am modeling the compressor foundation with pile supporting. my query is how to model pile  as spring in foundation model.</p><p>this foundation is dynamic analysis foundation and pile spring stiffnes consideration with dynamic pile stiffness.</p><p>can any one help me how to model pile as spring with dynamic pile stiffness.</p><p> </p><p>Regards</p><p>Ramesh </p>

<p>使用JC模型做打靶实验仿真，材料用的是钛合金，为什么我的结果是高温反而不容易破坏，是因为我在不同温度用的是同一套JC模型吗，但是JC模型不就是一套模型可以体现温度应变率的影响额本构模型吗</p><p>？</p>

<p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">Hello everyone,</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">I am new to LS-DYNA. As written in the title, I would like to ask for your help analyzing my energy plots to see whether my simulation is reasonable.</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">Description:<br>This is a model where a soft object (A) falls onto a rigid surface (B) from a small height with Gravity.</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">When I run the simulation, I get three cases:</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">1. Case 1: Object A has been simplified, with many parts removed, no added mass</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">If I do not add mass, the energy plot looks like this:</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;"> </span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">The total energy increases together with the kinetic energy. The kinetic energy is converted into internal energy after the impact.</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">But I don’t understand why the internal energy continues to increase even after the kinetic energy goes to zero.</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">Is this result reasonable? </span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">Or where might I have made a mistake?</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">2. Case 2: Added mass using ELEMENT_MASS</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">When I add mass to nodes using E_mass, these nodes become almost unconstrained after the impact.<br>The result is:</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;"></span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">In this case, the kinetic energy still remains.<br>How can I fix this problem with E_mass?</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">3. Case 3: Add more parts, reduce E_mass, apply BOUNDARY_PRESCRIBED_MOTION_SET</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">I added more parts back to the model, reduced the amount of E_mass, and applied BOUNDARY_PRESCRIBED_MOTION_SET at the top of object A.<br>The energy plot becomes like this:</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;"></span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">The nodes seem to be compressed and oscillate within a small range. The oscillation does not fully decay and looks like a sine wave.<br>But the energy looks more reasonable: Total energy = kinetic energy + internal energy.</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">Is it reasonable to use this BOUNDARY condition?<br>Is there a way to reduce the oscillation and bring the model to a steady state?</span></p><p class="MsoNormal" style="line-height: 115%;"><span style="font-family: 'Arial',sans-serif;">Please help me.<br>Thank you very much.</span></p>

大家好 我建立了风管和支架的模型 我想分析支架的受力 下一步我应该怎么做

lsprepost哪里有交流群或者其他的论坛之类的 我想去更多的论坛提问 之前有人分享过谷歌群组 但是进不去

<p>Hello everyone, </p><p>I am currently working in LS Dyna (workbench version). After the simulation was sucessful, i wanted to get the deformed geometry as I need to extract the fluid domain from the Spaceclaim and use the geometry further in the fluid structure interaction. The method i am using to get the deformed geometry is shown below in the photo. From the mechanical model (B) i can export the deformed geometry (.pmdb file) OR I can direcly drag the model (B) to geometry (C) and open the geometry in design modeler. While this method seemed to work in the ansys mechanical workbench in past, for LS Dyna workbench version, it doesn't export the actual geometry, rather just one or two curves. While i tried to open the geometry in the Design modeler, it first showed me an error of the agppi license error (see the photo) even though there are enough Disco_level1 (i think as the Disco_Level1 licenses are available, design modeler should use it first), and after some trial and error, when i got the .agdb file and saved it as the part file from the design modeler, the geometry was lacking most of the solids.  </p><p>Another method i tried was to export the .stl file and reverse engineer the .stl file to the actual geometry,  but due to the complexity of the geometry, and the requirements for the fluid structure interaction, the final output after the reverse engineering is useless. So is this a bug from the LS dyna workbench version or what? Because i tried to export some other geometry from the LS dyna as well (both deformed after the simulation and undeformed before the simulation). In each case it is exporting the empty .pmdb file.</p><p>That's why i wanted to ask that is there any other method to get the deformed geometry after the simlation (not through the .stl file or the method i showed in the pic)?</p><p>Thank you very much in advance for any kind of help!</p><p> </p>