ON THE DEVELOPMENT OF PRE-INVERTED TUBES FOR IMPACT ENERGY ABSORPTION MODULES

• Main Author: Putranda, Kevin
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/71160
• Institution: Institut Teknologi Bandung

Among the inversion modules, tubes are widely applied as impact energy absorbers. Pre-inverted tube, as a modification of the external inversion module mechanism with known characteristics, is currently being developed as an impact energy absorber. The main idea of this research is that the pre-inverted tube is one of the external inversion modules developed in order to absorb energy optimally and determine the characteristics of the module. In order to obtain the characteristics of the module, it is necessary to conduct a parameter study using Abaqus software. The modeling is simplified as a 2D-axisymmetric model and uses the Johnson-Cook material model which sets the material properties in the plastic area. Further design and process parametrization are required to obtain maximum results. These parameters are tube outer diameter (D), tube thickness (t0), the radius of dies (R), friction factor (?), oblique load (?), and material type. In addition, parameters are defined to determine the design effect of crashworthiness. This research was explicitly conducted with a numerical approach and validated with experiments. Dynamic load experiments (drop tests) were conducted on API 5L grade B material tubes for validation. The finite element analysis results were compared with the test and the results were close to the test with an error of 3.5%. By parametric study, the relationships between the non-dimensional input parameters (i.e. tube thickness ratio, t0/D and dies radius ratio, R/D) and impact characteristics (i.e. energy absorbed, EA and load ratio, Fss/Fy) are able to answer the design limits to prevent undesirable failure modes and geometry constraints for tube and dies are obtained. The maximum and minimum tube thickness ratio is 0.034 and 0.020, and the maximum and minimum dies radius ratio is 0.18 and 0.07. The coefficient of friction was varied and then compared with the test results where ? = 0.15 was obtained. With the variation of the impactor inclination angle ?, the module cannot absorb the impact energy maximally because the force response is getting smaller. From low-carbon steel to medium-carbon steel, the energy absorbed by the material also increases based on yield strength and carbon content. In this paper, based on the BS SNI 8826:2019 standard, the pre-inverted tube can be applied to the impact energy absorbing module for railway vehicles, namely Light Rapid Transit (LRT) in Indonesia. Using the impact characteristic equation, the optimal design geometry can be obtained for any application. For the case of the LRT train the module with an outer diameter of 219 mm with a stroke of 738.26 mm provides a total of 378.20 kJ of energy absorbed by the pre-inverted tube. The results were also verified using finite element software with an error of 6.72% based on the maximum force of the LRT.