Creep rupture tests on 3D-printed plastic foams

• Industry: Additive Manufacturing, Plastics Industry

For research and further development of the properties of 3D-printed plastic foams, a universal testing machine inspekt duo is used on which, in addition to simple compression tests, creep tests are also carried out at room temperature.

Creep rupture tests are used to determine the creep behavior of plastics under a constant load. In the creep test, the force or stress is kept constant for a certain time. During this process, the strain increases because the material flows/creeps. The testing machine measures the strain over the crosshead travel. The high resolution of the crosshead travel measuring system of the inspekt duo testing machine (<0.025 µm) ensures accurate strain measurement.

In addition, the testing machine is used to perform relaxation tests. These assume a constant deformation, whereby the decrease in stress as a function of time is registered in the test. In detail, during the relaxation test, the test specimen is loaded to a predefined compression. This state is maintained for a defined time in order to subsequently measure the force or stress drop.

The universal materials and component testing software LabMaster is used to perform and evaluate tests. The testing software includes all standard functions to perform creep tests and relaxation tests easily, comfortably and clearly. In order to keep the database fast and manageable during long-term tests, the data acquisition can be reduced during certain test phases. In most cases, less data is required for evaluation during the holding times of relaxation tests than during load application or unloading, for example. For metallic cellular structures, the in-house testing software LabMaster also allows compression tests according to DIN 50134.

For research and development, the testing machine is used to test specimens with different pore structures - from homogeneous to very inhomogeneous arrangements. The size of the pores and static elements is also variable. The specimens for material testing are each produced with a 3D plastic printer.