By the collision of cars, ships and offshore plants can cause enormous damage, including loss of life and environmental pollution. Therefore, the material properties of the high speed has been desired. General UTM (Universal Testing Machine) and high-speed tensile tester is different. The high-speed tensile tester is a material testing machine that measures mechanical properties such as tensile strength and elongation by applying a tensile load to a specimen at high speed.
High-speed tensile testing machine includes a number of vibration elements by impact force due to high speed. So the jig for supporting the specimen also vibrate. It is added to the load signal and vibration signal of the jig. Therefore, it is difficult to measure the load signal. The purpose of developing high speed tensile testing machine is in the load data obtaining accurate and reliable. The reason for the load ringing of the jig was analyzed. And to improve the load ringing studied international practices and domestic cases. As a result of the analysis, it was found that the vibration phenomenon is due to the natural frequency. Then, finite element analysis was performed as follows. First, we used a strain gauge and reduced the size of the jig. The material of the jig was made of steel, aluminum, and titanium. The second one is made of steel and the size of the jig is further reduced. And the length of the specimen was interpreted differently. The analytical results showed that there was no difference in load fluctuation between steel, aluminum, and titanium jigs of the same size. The reason is that even if the mass is small, there is no difference when the elastic modulus is low.
Through finite element analysis jig has been designed to improve the load ringing. The jig designed in this way was produced. The specimens were made as short as possible. The speed was set at 2m/ s, 3m/s, 4m/s and 5m/s. and specimen was made of SPHC. The pressure of the Hydraulic pump was set to 200 kg/cm2. The temperature condition is classified into room temperature high temperature and low temperature. However, this test was carried out under the conditions to be tested at room temperature.
It is difficult to measure displacement and velocity at high speed with a general displacement meter. We used a high - speed camera to measure speed and displacement at high speed, and a dynamic strain meter to collect load data at high speed. And it was evaluated by a high-speed tensile test.
In conclusion, in the test case and the finite element analysis, the load fluctuation phenomenon of the conventional piezo type load cell occurred due to the elastic modulus and mass of the upper jig.
Therefore, strain gauge type load cell was used to overcome the limitation of piezo load cell. In order to minimize the mass, a very compact split jig was used to minimize the mass, and a high elastic modulus steel was used. And the natural frequency can be increased and the amplitude can be reduced. Therefore, we obtained improved load data than conventional piezo type load cell and obtained load data similar to load data of quasi - static load.
As a result, it was possible to remarkably improve the load fluctuation caused by the mass of the high-speed tension jig.