Automation of Pneumatic Actuators for Testing of Small-Specimens Using Mini Load-Frames

Quasi- static and dynamic tests are an essential tool to study the performance of materials and structures. The results of these tests allow analyzing the behavior of the specimen in accordance with the type and magnitude of the stress acting on the specimen. Pneumatic actuators are a suitable option to simulate quasi-static loading on small specimens, since their cost is low when compared with other actuators. This article shows the results of the automation for pneumatic actuators attached to a mini load-frame. The characteristics and response of the mini load-frame system are initially described and discussed. It is then described the design of the control systems such as a classic PID and a self-tuning regulator, as well as the data acquisition and displaying systems. Finally, there are shown the results of tests executed in a real environment, operating the fully automated system and having implemented the force and displacement controls. The proposed automation for the pneumatic actuators is practical, low-cost and it increases the competitiveness, relevance, and validity of the results obtained by the various tests of materials and small structures.