# tosca topo

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ANSA v.13.x

Optimization with ANSA

Tutorial

OPTIMIZATION WITH TOSCATOPO OPTIMIZATIONTable of Contents1. Introduction.........................................................................................................................................2 1.1. Prerequisites ...............................................................................................................................2 1.2. What is the Topology optimization ..............................................................................................2 1.3. The Model...................................................................................................................................3 1.4. Optimization Task .......................................................................................................................4 1.5. Data files.....................................................................................................................................4 2. Recipe ................................................................................................................................................5 3. Preprocessing.....................................................................................................................................6 4. Start Optimization .............................................................................................................................13 5. Postprocessing - Viewing the intermediate results using TOSCA.post.............................................13 6. Result Transfer and Validation Run..................................................................................................14 6.1. Generating the surface using TOSCA.smooth ..........................................................................14 6.2. Modifying the surface using RECONSTRUCT ..........................................................................15 6.3. Remeshing the model ...............................................................................................................15 6.4. Saving the resulting model in solver format ..............................................................................16 6.5. Running the solver with the new model ....................................................................................16 7. Result Discussion .............................................................................................................................17

BETA CAE Systems S.A.

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ANSA v.13.x

Optimization with ANSA

1. IntroductionThis tutorial presents the set up of a simple Topo optimization task using TOSCA Structure Optimizer and the TOSCA Environment of ANSA. 1.1. Prerequisites - The user should be familiar with the basic functionality of ANSA and TOSCA Structure. - In this tutorial the NASTRAN solver is used and the model has been prepared to run to this solver. If another solver has to be used, the user must update the model properly.

1.2. What is the Topology optimization At the beginning of the conventional design process the design engineer defines the shape and the topology of new components using the experience and the results gained from the forerunner. This results in an evolution process which might lead to an optimum design after some iterations and a long period of time. Nowadays, it is necessary to shorten the development process of new components. Therefore tools are necessary that replace the natural evolution process by an automatic procedure. With TOSCA Structure it is possible to carry out topology and shape optimization in the CAE environment. Topology optimization is a tool to generate a design proposal and is often used within the concept finding for a new component. Starting with the design area which is the maximum allowed area for the component and with the boundary conditions, such as loads, fixtures and manufacturing conditions, the optimization system will determine a new material distribution by removing material from the design area. This design proposal fulfills all mechanical requirements and represents a weight-optimal design proposal. For the optimization the following constraints and objectives can be realized: stiffness (compliance and displacements) eigenfrequencies internal and reaction forces dynamic compliance dynamic displacements, velocities and accelerations weight, volume center of gravity moment of inertia

BETA CAE Systems S.A.

2

ANSA v.13.x

Optimization with ANSA

In addition, a number of manufacturing constraints can be applied so that the design proposal can be produced with casting or stamping. For this casting constraints, member size constraints, freezing, symmetry and coupling constraints can be defined. As result the optimization system creates a design proposal with the information where the material has to be positioned. This design proposal has to be interpreted and be used for the more detailed analysis. For supporting this step, the TOSCA Structure system supports the generation of a verification model within ANSA. This means a new model based on the results of the topology optimization can be created easily without the necessity of applying the loads and boundary conditions to the verification model. All loadcases and boundary conditions of the optimization model are transferred automatically to the verification model. With the results of the verification run it is possible to perform a normal FE postprocessing step within the postprocessing environement suitable for the relative solver. Alternatevely, a CAD model can be generated which then can be transferred back to the CAD system. 1.3. The Model The model for the topology optimization was modified in such a way that the inner areas of the component are filled with elements to create a design area. In that area, the optimization system can remove or rearrange elements for getting a better solution with lower weight and the same mechanical behavior. The start model for the optimization represents a design of a control arm for a car. The component has to be manufactured by forging and consists of aluminum.

The red areas of the component are not free for the optimization because they are used for the fixtures and for the load application. One red area is used for the mounting of a sensor for the headlight range adjustment. The fixture is realized with spring elements on the right upper red area. The springs represent a rubber bearing. The left bearing is fixed in all three translation degrees of freedom. As loading, a force is applied in the center of the lower bearing. Due to symmetry reasons only one half of the model is meshed so the symmetry plane is fixed in z-direction for ensuring the symmetry condition.

Optimization model representing the design area of the model.

BETA CAE Systems S.A.

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ANSA v.13.x1.4. Optimization Task

Optimization with ANSA

The optimization task is to find a structure with the maximum stiffness for the component with a volume or weight restriction. This represents the most common standard optimization task for the topology optimization. The value to be optimized is the compliance which is the reciprocal value of the stiffness. The compliance is represented as the sum of the strain energy of the complete model. This value has to be minimized. The constraint is the weight or volume constraint which is defined to be 57% of the initial volume/ weight of the structure. As manufacturing constraint a casting/forging constraint has to be defined. The idea of the constraint is to ensure that the created structure of the topology optimization has no undercuts and can be demolded (or removed from the forging die). 1.5. Data files The files of this tutorial are located in the directory /ANSA-installationdirectory/docs/tutorials/MORPH_OPTIMIZATION/tosca_topo/tutorial_files The file is: Control_arm_tosca_env.bdf initial FE-model in NASTRAN format Note: in case another solver is needed to be used,the appropriate input files are also located in the same path.

BETA CAE Systems S.A.

4

ANSA v.13.x

Optimization with ANSA

2. RecipeIf you have never worked with ANSA-TOSCA Environment before, skip this summary and go directly to the detailed description. If you do have some experience with ANSA-TOSCA Environment you can try to generate your parameter file just using the recipe summary. Recipe summary Preprocessing 1. Load the ANSA-TOSCA Environment Task in Task manager: Tasks> TOSCA Structure Task> TOPO_CONTROLLER. 2. Input file: PRE_PROCESSING> MODEL_LINK(NASTRAN)> New> FILE PRE_PROCESSING> MODEL_LINK>FILE> Update 3. Design area: PRE_PROCESSING> TOPOLOGY_OPTIMIZATION_CONTROLLER> DESIGN_AREA> Edit 4. Design constraints: PRE_PROCESSING> TOPOLOGY_OPTIMIZATION_CONTROLLER> DESIGN_AREA> DV_CONSTRAINTS 5. Objective function: PRE_PROCESSING> TOPOLOGY_OPTIMIZATION_CONTROLLER> OBJECTIVE_FUNCTION 6. Constraints: PRE_PROCESSING> TOPOLOGY_OPTIMIZATION_CONTROLLER> CONSTRAINTS 7. Saving TOSCA Structure parameter file: PRE_PROCESSING> TOPOLOGY_OPTIMIZATION_ CONTROLLER> Output Start Optimization 8. Running TOSCA Structure: START_OPTIMIZATION> RUN Postprocessing 9. Viewing the intermediate results: POST-PROCESSING> GENERATE_POST_FILE Result Transfer and Validation Run 10. Smooth surface: SMOOTH> SMOOTH_INSTANCE> RUN_SMOOTH 11. Modified surface: SMOOTH> SMOOTH_INSTANCE> VALIDATE> BATCH_RECONSTRUCT 12. Remeshing: SMOOTH> SMOOTH_INSTANCE> VALIDATE> SOLID_MESH 13. Saving the result: SMOOTH> SMOOTH_INSTANCE> VALIDATE> VALIDATION_OUTPUT 14. Running the solver: SMOOTH> SMOOTH_INSTANCE> VALIDATE> VALIDATION_RUN Please note that TOSCA Structure 7.0 is required in order to complete the optimization task. With previous

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