Design and Manufacture of Miniature Testing Machine for Composite Materials

Abstract

Today, there are many commercial test machines in industry and laboratory with many different sizes. However, their prices are high. Some laboratories made their own equipment at lower price based on their situation, demand and purpose of test. In this paper, the design of the frame structure and the operating systems, as well as the calibration of a small tensile and bending test machine for low- to medium-stiffness composite materials are presented. The construction is made of aluminum. The loading is created by an actuator which is controlled by an Arduino micro-controller. A Hocdelam USB-9090 (the same as that of NI USB-6009 but with less accuracy) data acquisition card is connected to a personal computer through an interface with load cell and strain gauge by the amplifier to record the force and the displacement during a test. The rate of loading is identified by the rate of actuator which is maintained stable thanks to the adjustment of PWM (Pulse Width Module) with Arduino. The machine is able to conduct tensile and bending tests with a loading up to 3000 N with a sensitivity of 1 N. It is possible to conduct tests on composite specimens at speeds of 1.7 ∼ 300 mm/min. This machine is able to obtain results for mechanical properties which are in good agreement with the data obtained from a commercial machine, the differences are less than 5%.