Test the Mechanical Properties of Articular Cartilage using Digital Image Correlation Technology

Abstract Articular cartilage is a kind of non-linear and viscoelastic connective tissue. A lot of attention has been paid to articular cartilage whose mechanical properties is unique due to the complex structure and environment. It is important to do detailed mechanical properties test in articular cartilage because it helps to reveal the principle of metabolism in cartilage tissue and can also offer references for the treatment of clinical cartilage disease and the repair of cartilage defects, etc. The traditional mechanical testing methods only reflect the macroscopic constitutive relationship of cartilage's mechanical properties, which is inaccurate and incomplete in analyzing the mechanical properties of cartilage. However, it is hard to investigate cartilage's mechanical properties in microscopic. Here the digital image correlation method is introduced to investigate the microscopic mechanical properties in cartilage. The equipment mainly includes image acquisition system, micro mechanical loading mechanism, control computer and image processing software. Capturing Image period is 0.5 s and loading rate is 0.01 mm/min-100 mm/min. The acquired images can be dealt with by image processing software and then displacement field, strain field and shear strain field are obtained. In this paper, the strain curve of cartilage from the surface zone to the deep was obtained by conducting compression tests for articular cartilage of the pig based on digital image correlation method. Compared with other methods, digital image correlation method is simple to operate and has low requirement for environment. By using this method the comprehensive mechanical properties for articular cartilage can be obtained.