AXIAL Crushing Of Thin-Walled Tube With Hole Under Quasi-Static Loading

Thin-walled tube is one of the energy absorbing structure utilized to dissipate energy and increase the efficiency of crashworthiness. During the accident, thin-walled tube dissipates the kinetic energy of the structure and converts it into other form of energy. Thus, this gives enough energy dissipation before hitting the human. This study examines the circular and square thin-walled tubes of mild steel subjected to axial crushing test by using Instron machine. These tubes include imperfection (round holes) located at three different locations. The theoretical results obtained from mathematical equations for the circular and square tubes crushing have been compared to the experimental results and a good agreement has been achieved between the theoretical and experimental results. The analysis of load-displacement characteristics includes the peak load, energy absorption capacity, mean crushing load, crush force efficiency (CFE), and specific energy absorption(SEA) results. The diameter, location and number of the holes were varied to investigate the effect of these parameters to the load-displacement characteristics. The location of round hole is located in 3 different level in the tube. As a result, the circular tube is capable of providing better decrease peak load and higher absorbed energy compared to the square tube.It was found that the better specimen is the circular tube with multi-hole, due to it has the excellent result in decrease the peak load reached to 16 %, it was concluded that value of the peak load is optimum in circular thin-walled tube. While the value of energy absorption slightly decreases in all specimens with holes compared with tube without hole. The location of holes in circular tube has the effect on the type of deformation. However, it does not affect the deformation in the square tube the location unaffected on the deformation. At the end, the modifications performed on the original tube shows an improvement in the load-displacement characteristics. The information obtained in this study will serve as a guide to better design the thin-walled tube in the future

The effect of cyclic twist angle on mechanical properties for AISI 1038 medium carbon steel

A group of 11 specimens AISI 1038 Medium carbon steel alloy fabricated according to ASTM standard D790-02 torsion test were twisted cyclically one in positive another to negative angle in range of angles (0o-50o), step 5 degrees for each specimen. The data from torsion test device help to get actual torques and shear stresses, later the specimens tested the tensile test to figure out the effects of cyclic angle of twist on mechanical properties for AISI 1038 Medium carbon steel. The results showed a good agreement between the theoretical and actual data (torque, shear stress) for specimens with positive angle of twist by the percentage: 98%, 91%, 96%, 93%, 91%, 89%, 88%, 85%, 82%, 81%, 80%. In other side the results for experimental tests showed a dangerous decrements in mechanical properties for cyclic or negative twist angles, the yield stress for reference specimen without twist angle is 490 Mpa, yield stress increased for angels (5o,10o,15o) by 1%, 3%, 6%, then decreased for angels (20o,25o,30o,35o,40o,45o) by 3%, 5%, 13%, 18%, 24% and 35% Respectively and the final specimen with 50o angle of twist had been broken torsional before tensile test as a result specimens groups consequent of the extrusion – intrusion defects concomitant from twisting load

Experimental and simulation study of mild steel response to lateral quasi-static compression

Collision of structure of a vehicle is not limited to the axial direction but it can occur laterally. The purpose of this paper is to present a study of the energy absorption behavior of different length of the circular mild steel tube under lateral crushing. A ring/tube (length of 10 mm, 35 mm, and 60 mm), 60 mm diameter and 1.5 mm thickness is compressed quasi-statically. Maximum loading setup to Instron machine was 50 kN. The speed of compression is 5mm/min. Finite Element Analysis (FEA) it used to validate the experimental work to ensure of getting accurate results. Numerical results of energy absorption and collapse load showed respectively 96.52% and 94.36% agreement with experimental results. The theoretical results showed 14.37% deviation with experimental and 15.5% with numerical results. The specimen with 60 mm length leads to better energy absorption than the other specimens. The results obtained numerically and experimentally in addition to theoretically showed the energy absorbed and collapse load varies with the length of the tube