Endpoint - Insertion Torque

2.0.52

This app replicates the bench test method described in ASTM F543-A2 standard to predict the insertion torque of metallic bone screws in Sawbones® rigid polyurethane foam. 

The whole simulation workflow is automated to :

1. Create the test geometry by importing the specified screw CAD file and creating the Sawbones® foam block around the screw in Spaceclaim,

2. Setup the analysis (Loading, Boundary Conditions, Contact Settings, Material Assignment and Mesh) in Mechanical

3. Solve the model in LS-Dyna

4. Create a simulation report and animation file.

This tool uses an advanced LS-DYNA damage and failure model to simulate foam failure during the screw insertion process. The only required input to evaluate pull-out performance is :

• the 3D CAD file of the screw (Step format).

• the value of the screw Insertion depth (in mm).

• Coefficient of friction (CoF*).

• Pilot Hole diameter (in mm).

Read the validation paper.

*:The predictive capability of the insertion model depends on having prior knowledge of the CoF between the screw and the Sawbones material grade [1]. The model’s sensitivity to this parameter means that uncertainties regarding the CoF can potentially impact the results. Therefore, providing an accurate value is crucial for utilizing the results in a predictive manner. In the event that the CoF is unknown, the model can still generate a prediction based on an estimated CoF. It’s essential to acknowledge the uncertainty associated with the estimated value, and results should be interpreted with caution in such scenarios. Nevertheless, the model can still be confidently used for comparative purposes in determining the relative performance or identifying the worst-case configuration among multiple screw designs. 

[1] Benoit et al. (2023) Validation of a virtual mechanical test for the prediction of screw insertion torque in Sawbones polyurethane foam in accordance to ASTM F543 standard.