One option for determining the life expectancy of materials is to measure the resistance to the mechanical long-term failure. This test method is significantly influenced by two sizes: One is through the crack initiation, which is the point at which the specimen begins to crack. The other is through the slow crack growth, which describes the progress of the crack at a non-critical cracking speed. Tests to date have been very time consuming and often required the use of additional thermal and chemical deterioration methods. These crack reducing wetting agents negatively impact the polymer structure of the specimen and distort the comparability with the material behavior under real conditions. The new test method to ISO 18489 reduces the test duration to a minimum. This is mainly attributed to the amount of cyclic loading depending on the specimen geometry. Another advantage of this test method is that it can be performed at room temperature so that the polymer structure of the specimen is retained. ZwickRoell developed theLTM testing system
with patented linear drive technology and force controlled pneumatic specimen grips for testing to ISO 18489. The testing machine's displacement measurement system is mounted in the piston rod coaxially and near the specimen, delivering an extremely precise measured value. The force controlled specimen grips reliably prevent the specimen from being overloaded during the gripping process. The wear-free drive and low power consumption ensure low ongoing operating costs. Therefore, ZwickRoell's LTM is ideal for efficiently testing pipelines made of thermoplastics to ISO 18489.