# florentb

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1. ## New design, determining preliminary rough geometry of a part to generate a design space for topology optimization in Inspire?

Dear Prakash Pagadala, Thanks for your answer. I realize maybe using the expression "design space" in my question was a bit confusing. Actually I am not asking how to select design and non-design spaces. I have a good understanding of that part of the process. For example, putting non-design space around functional surfaces and interfaces like holes, etc... To be more exact, I am looking for a "methodology" (or method, process, procedure, rules or guidelines) to determine a preliminary rough geometry to a mechanical part inside a mechanical system from a set of requirements. So I can use that rough geometry as my model on which i will define "design space"+"non-design space". Maybe my question will be much clearer if I use some examples: * Let's say you want to design a structural part for an Internal Combustion Engine. You can first determine an envelope (the maximum space/volume) of the part you are designing. One possible methodology would be to start with a large volume from which you will subtract the volume of all surrounding components. * Another example: You want to design a car structure. One possible methodology for example to determine the envelope of the structure you are going to optimize is to start from the styling envelope (the exterior volume of the car) and then subtract the volume of each component of the car and other volumes (like volume for occupants, volume for the trunk, etc) from the styling envelope. Once you have obtained that "structure envelope" you will still have to define design and non-design space to keep interfaces, attachment points, etc... In the previous examples I gave, you see you already have a lot of information (volume of the system, volume of components, etc) available for your design, you can easily create a model and then select design and non-design space. If I go a bit further, let's say I want to design an innovative mechanism with some different and non-standard components/bodies. I would start the preliminary design process by defining the topology of the mechanism. For that, I will maybe draw a kinematic diagram (also called kinematic scheme or skeleton diagram). But the next step is to give a preliminary rough shape to each body (embodiment design) so I can then use topology optimization to find an optimal "final" geometry. "Finding a preliminary rough shape" is not so obvious for me. I think the shape has to be chosen carefully to avoid missing some good alternative structural concepts. The only methodology is see at the moment is the old "trial and error" but I am looking for a more systematic methodology. I am aware that my question goes far beyond simply using Optistruct/Inspire and it is more a methodological question. As I said in my initial question, I think it actually deals mainly with configuration design (arrangement of the individual components, determination of interfaces, space allocation, etc.). By the way, as I think some of you are experienced mechanical engineers maybe you will be able to give me some advices or some lines of thought. Sorry for my imperfect English. Thank you. Kind Regards, Florent