A portable fracture toughness tester for biological materials

TLDR

The study presents a lightweight, inexpensive portable mechanical tester designed for measuring fundamental mechanical properties of pliant solids. The tester employs a novel hardware integration technique with integrated circuits, enabling force–displacement measurements without a chart recorder and allowing linkage to a PC, while its lightweight frame and load cell minimize errors in soft material tests. The machine is simple and convenient to operate, requires minimal training, and successfully measured toughness of biomaterials such as paper, wood, and mung bean starch gels using scissors and wedge tests.

Abstract

A portable mechanical tester is described which is both lightweight and cheap to produce. The machine is simple and convenient to operate and requires only a minimum of personnel training. It can be used to measure the fundamental mechanical properties of pliant solids, particularly toughness (in the sense of `work of fracture') using either scissors or wedge tests. This is achieved through a novel hardware integration technique. The circuits are described. The use of the machine does not require a chart recorder but it can be linked to a personal computer, either to show force - displacement relationships or for data storage. The design allows the use of any relatively `soft' mechanical test, i.e. tests in which the deformability of the frame of the machine and its load cell do not introduce significant errors into the results. Examples of its use in measuring the toughness of biomaterials by scissors (paper, wood) and wedges (mung bean starch gels) are given.