In this study, the combination of an expansion tube and a deformable rigid tube with axial splitting is developed as a new mechanism for use as an impact energy absorber. The impact absorbing structure consists of two circular tube forming dies, with each die allowing the tube to expand and to split. The latter is used to remove away radially the debris after expansion and splitting, so that the absorption process can continue without being obstructed by the debris itself. This paper presents the experimental and theoretical investigation of the combined expansion tube-axial splitting as an impact energy absorber. The experiment by the laboratory scale impact testing has been done with a variation of the parameters such as pipe thickness ([Formula: see text], angle of splitter ([Formula: see text], comparison of dies upgrading diameter ([Formula: see text] and inner pipe diameter ([Formula: see text] ([Formula: see text]/[Formula: see text]. The theoretical investigation is carried out with a literature study related to the mechanics of material and theoretical studies from previous research studies. The final result of this paper, i.e. a new formula proposed to calculate the mean load, is reflective of the study of a combined expansion tube with axial splitting. The difference between the results of analytical calculation and experiments is 10.13%.
The airfoil profile of this study is based on plant morphology, which is rarely modeled in airfoil profiling. Designing, modeling, and analyzing the aerodynamics of one of the projected morphological parts of the banana leaf midrib that forms a 45-degree angle with the longitudinal axis as a distinct new airfoil. The profile of the LM-45 airfoil has a thickness of 16.28%, a chord length of 1500mm, a Reynolds number between 3E5 and 7E5, and a wind speed between 3 and 7 meters per second. An aerodynamic analysis using QBLADE and ANSYS FLUENT determined the glide ratio and pressure distribution across the airfoil surface. LM-45 has a maximum glide ratio of 123.07 at an angle of attack of 2 degrees and a Reynolds number of 7E5, and a minimum glide ratio of 70.02 at an angle of attack of 4 degrees and a Reynolds number of 3E5. As indicated by the glide ratio, the banana leaf midrib profile can be applied to the airfoil profile for wind speeds between 3 and 7 m/s at an attack angle between 2 and 4 degrees.
Adhesive joint is commonly applied to CFRP/GFRP composite tube, however, its failure rate is still high and this will limit the use of composite tube for industrial purpose. The literature study showed that the stress distribution at the joint, when loaded, is not evenly distributed and creates stress concentration at the edges. Attempts have been made by researchers to improve the joint design so that the stress would be more evenly distributed and minimize stress concentration, however, the improvement has been very limited. In this work, a comprehensive parameter study has been performed to observe the properties of adhesive joint of torque loaded tube. Based on the observation, a new type of adhesive joint is proposed which successfully reduces the stress concentration along the joint during torque loading. The analysis was performed using finite element method.
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