Mechanical Properties of Biological Materials

Abstract

When we want to design, that is, prepare a drawing and fabricate something to replace a desired body part or malfunctioning organ(s) due to disease processes, trauma, or surgical removal, it is necessary to understand the real nature and biomechanical characteristics of those anatomical parts, e.g., tissues and organs. Anthropometry is the science and practice of measuring the size and shape of the human body and its parts. To measure the properties of biological materials and tissues are also anthropometry’s tasks. Biomechanics, in turn, studies the structure and function of biological systems using the methods of mechanics. The composition and behavior of bones, cartilages, and ligaments have been studied for many years. However, although we know much about these tissues, newer and better measurement techniques continuously improve the available data. It should be remembered that there are biological variations and environmental factors that significantly affect the mechanical properties of biological tissues.

Problems

• 1. List a total of five metallic, polymeric, ceramic, and composite biocompatible materials.

  List their compositions and mechanical properties, such as ultimate strength, yield strength, ultimate strain, and hardness. In a single plot, draw their stress–strain diagram under tensile load with approximate scale indicating the yield point, ultimate strength, and modulus of elasticity.

• 2. List names of some hard and soft tissues in the human body. How do we characterize them? Show their stress–strain diagram.

• 3. Compare the hardness of different components of teeth. What materials will be suitable for the replacement of teeth?

• 4. The following figure shows the load deformation diagram of a scaffold of chitosan–hydroxyapatite composite mixed in different proportions. Discuss the effect of HA on the ultimate strength and the primary and secondary moduli of elasticity. The cross-sectional area may be taken as 15 × 10 mm² (based on a 2007 biomedical engineering master’s thesis at Jadavpur University). The starting point of each plot is (0, 0).