Topology Design of a Compliant Mechanism
Product = GTAM/GSAM
Genesis® for Ansys® Mechanical (GSAM/GTAM) adds the power and versatility of Genesis® structural optimization capability to the ANSYS environment. Engineers can enlist the rich breadth of Genesis® optimizations, performing optimization data definition, solving, and post-processing all within the Ansys analysis systems. In this article, we would like to show how to perform topology optimization to design a compliant mechanism.
Loading Conditions
There are two loadcases defined as shown in the image below. In the first loadcase, the structure is fixed on the top surface, enforced displacement are applied along X direction on the two side surfaces and along Y direction on the bottom surface. The objective is to find a structural configuration that provides preload as output at the bottom surface when pressing from the two side surfaces. The second torsional loadcase is added to make sure the structure has certain stiffness in z direction.
Figure 1. Loadcases.
Optimization Problem Definition
In ANSYS Mechanical, we add the Objectives, Constraints, and Topology Regions to the GENESIS system, and define the corresponding data as described below.
- Objective 1: Maximize the sum of reaction force along Y direction at the bottom output surface for loadcase 1
- Objective 2: Minimize the strain energy for loadcase 2
- Constraints: mass fraction < 0.2
Optimization Result
The optimization finished with 50 cycles. The topology density isosurface result is shown as below
Figure 2. Topology Density Isosurface Plot
The deformation animation plot after optimization is also shown as below
Figure 3. Deformation plot
Summary
Topology optimization created a structure that is flexible in x direction, such that when pressing along x direction, the bottom surface goes downward and applies compression to the device in contact with it. The objective improvement is shown in the table below.
Figure 5. Summary in GENESIS
Topology optimization is a great tool in GSAM, which is easy to set up but also very useful for design improvement and innovation. For more details, leave a comment below.