Solving Beamy - Three-Point Bending Test

Three-point bending tests are a common way to evaluate the structural integrity of mechanical components and ensure they meet required displacement/force criteria. A typical test setup for this type of test is shown in Figure 1 below.

Figure 1 – Typical Three-Point Bending Test

Finite Element Analysis (FEA) is often used to mimic these types of tests, allowing for product designers to avoid costly physical prototypes and setting up physical tests. Beamy produces a high-tech speaker, and we are going to try and use SOLIDWORKS Simulation Premium to perform a three-point bending test on an internal bracket for one of these speakers, see Figures 2-3.

SOLIDWORKS Simulation is a powerful integrated solution that many designers and analysts use for their day-to-day simulation needs. This example is a little more complex than most. While it appears to be a fairly straightforward analysis, the sliding contacts between the chassis and the rods, coupled with the nonlinear material behavior of the chassis, which made of a high-impact acrylic whose material properties are shown in Figure 4, make this a highly nonlinear problem.

Figure 4 – Acrylic Chassis Material Properties

The setup of the problem is simple inside of SOLIDWORKS Simulation; we define a no-penetration contact between the rods and the chassis with an appropriate friction coefficient, which is shown in Figure 5 below. We also fix the bottom two rods and apply the appropriate displacement to the push rod, standard boundary conditions for this type of analysis.

Figure 5 – Contact Conditions in SOLIDWORKS Simulation Premium

This solution requires some “massaging” of the default solver settings because there is local buckling in the chassis where the push rod makes contact. It also takes over 25 minutes for this solution to fully converge. A displacement plot is show in Figure 6 below. For this type of analysis, 25 minutes seems a bit excessive. While it’s great to be able to get a converged solution, the solution time and the need to tweak the solver settings make it difficult to run multiple simulations or do a simulation-driven product design.

Figure 6 – Displacement Results in SOLIDWORKS Simulation Premium

One of the many benefits of using a solution like SOLIDWORKS and SOLIDWORKS Simulation, is that they are both part of the larger Dassault Systèmes ecosystem. Within that ecosystem are various tools that can be used to solve problems like this in a timely manner. In the upcoming blog posts we’ll take a look at using the 3DEXPERIENCE platform and solutions from the Simulia brand to solve this problem.