Within the scope of research and final theses, the Institute for Materials and Application Technology Tuttlingen (IWAT) of the Furtwangen University in Germany has worked in cooperation with ZwickRoell for a number of years. To determine the strength characteristic values of additively manufactured metal components, mechanical tests are performed in the ZwickRoell laboratory.
The test was performed within the framework of master thesis „Konstruktion und additive Herstellung verschiedener poröser Bauteile sowie deren Charakterisierung durch röntgencomputertomografische Methoden“ [Design and Additive Manufacturing of Various Porous Components and their Characterization by X-Ray Computed Tomographic Methods], under the supervision of Professor Mozaffari-Jovein and Mr. Pede. The test is based on DIN 50134 “Testing of metallic materials – Compression test of metallic cellular materials”. This test series is used for the determination of mechanical properties of additively manufactured, porous components under uniaxial compression loading.
The test is performed on built, porous titanium components with different grid structures. Each grid structure is built in two versions (400 and 500 μm strut thickness). The outer contour of the components is 20 x 20 x 36 mm, including a 3 mm border at the top and bottom. The grid structure comprises 10 x 10 x 15 cells.
The force application on the testing machine takes place between two plane-parallel, ground and lubricated plates with a minimum hardness of 60 HRC. They can be lubricated with graphite, for example. One specimen is required to run a pre-test to estimate plateau stress. The actual test is performed on three specimens per grid structure, to determine the mechanical properties. Before the test, the width of each specimen is measured on at least three measuring points. The average cross-section is used as the initial cross-section value for the compression test. The outer surfaces of the borders are ground to achieve a smooth contact surface between the test plates, and they have to be parallel.
The tests were performed in the ZwickRoell testing laboratory using an AllroundLine testing machine (Fmax 250 kN).