Dario Alonso

Good evening, I am making a Formula SAE impact attenuator simulation. It is make with carbon fiber prepreg. For the model we are using material LAW 25 (CRASURV) and property 17 (stack). To calibrate material parameters and boundary conditions we are simulating an small plate. During the impact we obserb a shock wave that brakes the plate wherever and not row by row. We are trying to include something to damp or relax the material avoiding the shock wave. However, when we use the control cad /DYREL the model stops and kinectic energy evolve to cero. Parameters used on /DYREL are relaxation factor = 1 (default) and period (6e-5). We obtain period following indications of this text (https://insider.altairhyperworks.com/wp-content/uploads/2012/01/DynamicRelaxation_1201.docx). Where is our mistake? What can we try to solve it? Moreover, we create a model to compare with a test made in our center 2 years ago. Real part have a maximum of 10 plies. To obtain the same results on our hypermesh model we have to use more than 70 plies. We have asked Altair Spain and they don't see any mistake on the model (Attached you can find the model) and recomend us to ask on the forum. Real test results were positive and the impact attenuator resist impact and there was 16 cm without brake. On the model the impact totaly brakes and can't stop the 300 Kg rigid body used to simulate the car. Thank you for your help modelo ingenia SI.hm

Hello, Sorry for ansewring so late. I solve the problem using different laminates and different properties for each zone. My version is Hypermesh 2017.2. When i change the element orientation i select all the elements of the face. Now i will try your solution using only one laminate. Attached you can find a model where you can see what i've done. Thanks for your help and sorry again for my late answer. MODELO 4-B.hm

Hello, I am creating a model for a carbon fibre impact attenuator. I need to align the orientation of the elements to make the simulation. As you can see on the figure 1 all the elements are align in X direction except the elements of the fron face. When i select this elements and i change its direction (figure 2) change all the model as you can see in figure 3. I tried to do it from diffrent ways but anything works. How can i align the elements of the front face without change the other elements orientation?