topic What happens if you mix rigid and weighted links sharing the same elements? in Analysis
https://community.ptc.com/t5/Analysis/What-happens-if-you-mix-rigid-and-weighted-links-sharing-the/m-p/675323#M2958
<P>Hello all.</P>
<P> </P>
<P>I´ll post again something that I have included in another post (<EM>Question about weight link and distance of the dependent side</EM>) – but now with a new interpretation.</P>
<P> </P>
<P>Creo Simulate has a classical example that a component is replaced by a point at CG and its mass. This CG point is connected to respective anchor points.</P>
<P> </P>
<P>An example would be a motor block connected to a frame. The goal is to verify the eigenfrequency of the frame. To include the motor block in the meshing is thus not needed. CG and mass (or advanced mass) is enough.</P>
<P><BR />If the CG of the motor is connected to the beds via rigid links the eigenfrequency of the frame is completely different than using weighted link – nothing new here.</P>
<P> </P>
<P>But we can also think that the block is rigid enough – but not really the connection. <BR />Each motor-frame connection transmits only forces – but not moments. A ball joint link. This should be possible to simulate but it would require one weighed link for each connection.</P>
<P> </P>
<P>Attached is my idea how I mixed rigid and weighted links. The model was copied from my original post and do not represents exactly the motor block case although the main idea is there.</P>
<P> </P>
<P>However, I figured out that the distance of the dependent - independent side of the weighted link changes the eigenfrequency result. I was not expecting this, as commented in the other post.</P>
<P><BR />This was a kind of surprise and made me to think again the general Simulate example of using the CG and a mass attached on it – if it is modeled using more than one weighted link. The original case uses just one weighted link connecting the CG to the frame. It is the classical modelling case.</P>
<P><BR />The result will be influenced by the distance of the CG (dependent side) and the connections (independent side).</P>
<P> </P>
<P>Maybe mixing rigid and (several) weighted links can create a compromise of frame stiffness – or even open new ways to prepare a simulation model. But it can be also a mistake for reasons that I cannot understand.</P>
<P> </P>
<P>For this reason, I´m looking for some advices.</P>
<P> </P>
<P>Thanks</P>Thu, 02 Jul 2020 12:54:43 GMTrrabe2020-07-02T12:54:43ZWhat happens if you mix rigid and weighted links sharing the same elements?
https://community.ptc.com/t5/Analysis/What-happens-if-you-mix-rigid-and-weighted-links-sharing-the/m-p/675323#M2958
<P>Hello all.</P>
<P> </P>
<P>I´ll post again something that I have included in another post (<EM>Question about weight link and distance of the dependent side</EM>) – but now with a new interpretation.</P>
<P> </P>
<P>Creo Simulate has a classical example that a component is replaced by a point at CG and its mass. This CG point is connected to respective anchor points.</P>
<P> </P>
<P>An example would be a motor block connected to a frame. The goal is to verify the eigenfrequency of the frame. To include the motor block in the meshing is thus not needed. CG and mass (or advanced mass) is enough.</P>
<P><BR />If the CG of the motor is connected to the beds via rigid links the eigenfrequency of the frame is completely different than using weighted link – nothing new here.</P>
<P> </P>
<P>But we can also think that the block is rigid enough – but not really the connection. <BR />Each motor-frame connection transmits only forces – but not moments. A ball joint link. This should be possible to simulate but it would require one weighed link for each connection.</P>
<P> </P>
<P>Attached is my idea how I mixed rigid and weighted links. The model was copied from my original post and do not represents exactly the motor block case although the main idea is there.</P>
<P> </P>
<P>However, I figured out that the distance of the dependent - independent side of the weighted link changes the eigenfrequency result. I was not expecting this, as commented in the other post.</P>
<P><BR />This was a kind of surprise and made me to think again the general Simulate example of using the CG and a mass attached on it – if it is modeled using more than one weighted link. The original case uses just one weighted link connecting the CG to the frame. It is the classical modelling case.</P>
<P><BR />The result will be influenced by the distance of the CG (dependent side) and the connections (independent side).</P>
<P> </P>
<P>Maybe mixing rigid and (several) weighted links can create a compromise of frame stiffness – or even open new ways to prepare a simulation model. But it can be also a mistake for reasons that I cannot understand.</P>
<P> </P>
<P>For this reason, I´m looking for some advices.</P>
<P> </P>
<P>Thanks</P>Thu, 02 Jul 2020 12:54:43 GMThttps://community.ptc.com/t5/Analysis/What-happens-if-you-mix-rigid-and-weighted-links-sharing-the/m-p/675323#M2958rrabe2020-07-02T12:54:43Z