University (TU) Braunschweig: fatigue-testing joining-technology

In the field of lightweight construction, composites are the future. Certain critical challenges must be overcome, however, if long-term commercial success is to be guaranteed. These include structure manufacture and, in particular, joining technology. The Institute of Joining and Welding (ifs) at the TU Braunschweig, Germany is working on the development of joining processes suitable for fiber composites and featuring a high degree of automation, process reliability and process velocity. For determination of the fatigue properties of these joining technologies the Institute uses a Zwick servo-hydraulic testing machine.
HC25_01_without background

Among  lightweight materials, fiber-reinforced plastics offer very high potential for lightweight construction. The unique properties of this composite material have led to a substantial increase in its percentage use in a wide range of industries. However, high material and process costs represent a  frequent barrier to large-scale use, with the consequence that the use of fiber-composite materials is often only justified when small quantities are involved. Research at the Institute is therefore concentrated on innovative manufacturing and joining methods designed to make a crucial contribution to cost reduction, thereby opening up new markets for fiber-composite materials.

To determine the mechanical properties of joints the Institute uses a Zwick servo-hydraulic testing machine. The HC25 Compact (Fmax 25kN) is equipped with a T-slotted platform, allowing easy mounting of different components for testing. In addition to classical fatigue tests, pulsating tensile-shear tests, pulsating compressive strength tests and hysteresis determination are carried out on epoxy specimens. The testControl II measurement and control electronics feature high (24-bit) measured-value resolution, guaranteeing maximum test-result accuracy and reproducibility and enabling the smallest changes in force on the joints to be recorded and displayed accurately.