Identifier

etd-050207-155719

Abstract

Twenty five porcine knee collateral ligaments were tested to determine the dynamic failure properties of ligaments. A test fixture, to be placed in a drop tower, was designed to apply an axial impulsive impact load to a porcine bone-ligament-bone complex. The applied strain rates ranged from 0.005s-1 to 145s-1. The data from the impact tests was analyzed using the method of linear regression to construct predictive model equations capable of forecasting the failure load and failure stress of a ligament subjected to a specific strain rate. 73% of the ligaments tested failed via tibial avulsion while the remaining ligaments failed via mid-substance tearing. The failure: load, strain and stress all increased with the applied strain rate. Further an interesting correlation between geometric ratios, namely the initial length divided by the initial cross sectional area and vice versa, and the failure load and stress were identified. Using this information, model equations were developed that predict the failure stresses based on the load and strain rate. The motivation for this study was to develop failure properties that could be used in an LSDYNA finite element model of the human lower extremities based on the understanding that the properties of porcine knee collateral ligaments would be similar to human ligaments. The properties developed in this study can be used to estimate the human response in high speed frontal automotive collisions.

Publisher

Worcester Polytechnic Institute

Degree Name

MS

Department

Mechanical Engineering

Project Type

Thesis

Date Accepted

2007-05-02

Accessibility

Unrestricted

Subjects

Collision, Automotive, Properties, Failure, Ligament, Ligaments, Testing, Fracture mechanics, Knee, Regression analysis

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