OENG1189 – Structural Optimization and 3D Printing
Assistance on Project 3
-Optimization Software
Q1: Could we use any tools available to use to do our Assignment 3?
A1:
For the outer shell (part 1), you need to use the most recent learned tool (Abaqus/Tosca) to optimize it in your assignment 3. For partitions (part 2) you could use BESO2D software.
Only students in groups with special considerations caused by group forming, ELS, other accessing problems could use MATLAB code as their tools to do optimization.
Assistance on Project 3
-Tosca Issues
Q2. I always encounter errors when I use Abaqus-Tosca, what I should do to avoid it?
A2: The likely reasons are:
(1) Your optimization settings (including loading and boundary conditions) are not appropriate which may not end up with a feasible optimal topology, so the Tosca model will be terminated abruptly. (If you run this model several times and it always terminates at Internation 12.
(2) There could be an internet connection issue in Iteration 12 (When you run the same model, it terminates at different iterations).
(3) You fail to keep your log in session active during the optimization process.
You may consider to do it at RMIT computer labs if you think the problem lies in internet connections
QA for Assignment 3
Q3.Could I do Assignment 3 individually?
A3: Yes, you can do it individually, however, Assignment 3 is a group assignment, and if you could not find a group (up to 5 students) to work with, you may lose up to 8 marks.
No penalty will be applied even if you work in a group of 2 students, however, if your group have more than five students, penalty will be applied.
Q4. I just would like to know what is a reasonable amount of cycles (where we would not lose marks) to use for the tosca optimisation for our 3rd assignment?
A4: Your optimization should converge to an optimal solution, i.e., evidenced by optimization history with the sufficient maximum iterations i.e. 55 or more and the optimization stops at iteration 32. If you set max iteration is 55 and your optimization stops at 55 and you may need to set a larger number or revise your optimization setting.
Q5. Do we need to get our optimised design and then adjust the model to reduce tension, or do we need to minimise tension/maximise compression our optimisation objective from the start?
A5: We will use the matured objective, i.e., maximize the overall stiffness or minimize the mean compliance (Strain Energy in our tutorial example) . After we obtain an optimal design, then we will check its printability.
Q6:Do we conduct the FEM analysis (verification and validation) on the whole structure once we optimise individual parts OR Do we conduct the FEM on individual parts?
A6: The right FEM is built, verified and validated on one part of the whole model with optimal topology(at least two parts).The partition part is relatively easier.
Q7. The number of different innovative deigns preferred hasn’t been mentioned anywhere how many alternative designs including the final optimal design would you suggest we consider?
A7:No detailed requirements (rubrics) on innovative designs. One set of the whole model (partition and outer shell) is sufficient for rendering. When you do printability check, alternative innovative designs for one part of your model may be required to demonstrate effectiveness of different ways to improve printability.
Q8. Is the bonus marks for Assignment 3 on top of 40 marks?
A8. No. You will get your bonus mark when you select the challenging models, then your final mark for Assignment 3 will be capped at 40 even if you will get 41 to 45.
Q9. How do I know how many points of connection to make on the partition wall and how do I know how thick I make part 2?
A9: You may find the thickness of the shell or partition from the 3D digital model provided to you when you confirm your selection of the structure and the site.
Q10. We optimize the SS and Dome using shell model and we want to do right FEM for SS, how could we obtain the load acting on the connections?
A10: Two possible approaches,
(1) build an axisymmetric model following week 10 tutorial task 1b (or 2b) obtain the load using contact forces;
(2) Using deformation level (or stress using pressure and von Mises stress component) to estimate the pressure load only (pressure and traction).
Q11. What kind of simplified model to use to do validation of the right FEM of SS or the whole structure?
A11:
You may use one or three (column+beam) (bar with rectangular section) to simplify the geometry. The theory of the deformation of each column+beam is PL/EA+TL3/EI, where L is length of the bar and A is the area of the cross-section, I is the second moment of inertia for the beam, P is pressure * area, T is traction *area
If you are from PCPM, this part is exempted.
Q12. I followed the video for task 4 in week 10 to get the sketch and save it using "Create cut: extrude" tool in part. However every time I save that sketch is empty with no drawings at all.
A12: You may notice an error after you click the “save sketch” button as “No section found, draw a sketch”. You need to draw the sketch before save it. The easiest way is to use the “Offset curves” , select all edges and offset them with a very small offset distance, i.e. 0.001.
Q13. Errors in Abaqus/Tosca on RMIT MyDesktop as shown and I can not run it. Should I contact ITS to fix it?
A13: No you do not need to ask ITS to fix it. If you scroll down and see the “OK”, then click it and your optimization procedure will move on. You may click this type of windows several times before you obtain an optimal design. Do remember to keep your account and session active during optimization process.
This QA will be updated from time to time, please check here first before you ask me a question. Thanks.