# Homework and Quiz - Modeling of Stents

### Homework, Part 1

In the lesson “Geometric Representation of Stent,” we discussed Ansys Spaceclaim's capability to model the stent. If the stent has a repetitive pattern, can Spaceclaim take advantage of symmetry (cyclic or translational)? This homework provides tips on using “repeating sections” such as wrapping one section of the stent and then copying/mirroring it to create a full-length stent. Perform the homework and answer the questions in the homework-based quiz. Download the instructions and simulation files here.

• Please utilize the mm, kg, N unit system when solving the Ansys simulation models.
• Please also note that the results you obtain in these nonlinear analyses may differ slightly from those shown in the videos. Numerical round-off due to finite machine precision can be affected by the choice of the operating system, the number of cores, and the type of parallel processing (shared-memory vs. distributed-memory). Moreover, nonlinear contact and solution algorithms are often improved in each version of our software, so some changes are expected when comparing results between different releases. Thus, your results may differ slightly (within typical engineering tolerances) from the presented results, but this is to be expected for nonlinear analyses, especially for numerically unstable (e.g., underconstrained) models that may be utilized in this course.

### Homework, Part 2

In lesson 4, we saw the expansion, shape setting and crimping of the ASME stent. Using the same approach and the same material properties as in the Workshop, demonstrate the expansion, shape setting and crimping of a quarter-symmetric stent model. Perform the analysis and answer the questions in the homework-based quiz. Download the instruction, geometry and simulation files here.

• Please utilize the mm, kg, N unit system when solving the Ansys simulation models.
• Please also note that the results you obtain in these nonlinear analyses may differ slightly from those shown in the videos. Numerical round-off due to finite machine precision can be affected by the choice of the operating system, the number of cores, and the type of parallel processing (shared-memory vs. distributed-memory). Moreover, nonlinear contact and solution algorithms are often improved in each version of our software, so some changes are expected when comparing results between different releases. Thus, your results may differ slightly (within typical engineering tolerances) from the presented results, but this is to be expected for nonlinear analyses, especially for numerically unstable (e.g., underconstrained) models that may be utilized in this course.

### Homework,  Part 3

In the lecture, we have introduced simulation methods to crimp and expand a stent and evaluate outputs such as the expanded diameter, foreshortening, chronic outward force and so on. Although a cylindrical shell is used as a virtual crimper in the lecture, there are multiple ways to model the crimping and expansion process. In this homework, you are encouraged to try a group of virtual arc-shaped crimpers and obtain the design variables. This is an alternative loading approach and it requires more effort in pre-processing and setting up the boundary conditions.

The geometry, material and crimping procedure are the same as in the workshop example in lessons 1 - 5. As a starting point, the stent shape setting process is already conducted (the stent is ready to be crimped). Follow the instructions in the readme file and the video, and answer the questions in the homework-based quiz. Download the instruction, geometry and simulation files here.

• Please utilize the mm, kg, N unit system when solving the Ansys simulation models.
• Please also note that the results you obtain in these nonlinear analyses may differ slightly from those shown in the videos. Numerical round-off due to finite machine precision can be affected by the choice of the operating system, the number of cores, and the type of parallel processing (shared-memory vs. distributed-memory). Moreover, nonlinear contact and solution algorithms are often improved in each version of our software, so some changes are expected when comparing results between different releases. Thus, your results may differ slightly (within typical engineering tolerances) from the presented results, but this is to be expected for nonlinear analyses, especially for numerically unstable (e.g., underconstrained) models that may be utilized in this course.

Completed simulation files for the above examples can be found here.

Lesson Content