Papers by Keyword: Rib

Abstract: Many industries and automotive companies use thin-walled cylinders as energy-absorbing devices. Researchers have previously investigated various parameters related to thin-walled cylinders and their behavior under impact loads. When the impactor hits the thin-walled cylinder from the axial direction, it causes the bending of the cylinder wall on an axisymmetric or non-axisymmetric pattern, depending on the ratio of diameter divided by wall thickness. In addition, the length of the specimen influences the deformation mode that occurs. This study discusses how installing ribs on the cylinder walls affects energy absorption capabilities. We conducted the research by making modeling based on the finite element method by making various specimens according to the experimental scenarios. We experimented with an aluminum alloy cylinder with a diameter of 50 cm, a thickness of 1.5 mm, and a length of 200 mm. Then, successively, we installed ribs with a length of 2 mm and a thickness of 3.5 mm, one rib, two ribs, three ribs, four ribs, and five ribs. The impactor hits the specimen from the axial direction to one end at high speed while the other is given fixed support. The results obtained from the experiment are total deformation, reaction force, absorbed energy, and deformation pattern. The experimental results show that adding ribs changes the deformation pattern from previously non-axis-symmetric to axis-symmetric. The total deformation decreases, the reaction force becomes smaller, and the ability to absorb energy equals the total kinetic energy. This result is a recommendation for manufacturing in an energy absorption structural system. Keywords: rib, deformation mode, wall thickness, energy absorption, reaction force.

Abstract: Rigid-hulled inflatable boats are extremely practical and popular nowadays. They offer a valid compromise between flexibility, handiness, performance and, finally, costs, supporting the pleasure of sailing. Their large use entails the fact that these crafts can be subjected to very different sailing conditions. The design has to be stable and seaworthy, mainly assured by hydroplaning hulls and unsinkable inflated tubes. When they are designed with extremely performing hydroplaning hulls, since their low weight, these crafts are able to outperform several types of similarly sized and powered boats. In the current study, experimental mechanics techniques were used to measure the strains showed by a rigid-hulled inflatable boat during sailing. Measure were used as a base for further considerations toward the design optimization of the hull in fiberglass.

Abstract: The influence of local buckling on the bearing capacity of light steel thin-walled profiles is a hot topic today. In this paper we evaluated the effect of the thickness of the elements of the cross section on bearing capacity the profile in a transverse bending.

Abstract: Local buckling and accounting of the geometric nonlinearity of light steel thin-walled profiles is an important topic. The authors assesses the influence of geometric nonlinearity on the bearing capacity profile in transverse bending conditions.

Abstract: Work is devoted to the actual topic - local buckling of light steel thin-walled sections. Method of calculating stability in thin-walled structures described in the work. The mechanisms of local buckling under transverse bending considered by authors.

Abstract: Most methods for calculating bearing capacity profiles section of complex shape local buckling (LPA) are ignored. The problem of LPA rod is reduced to the problem of overall sustainability. At the design stage constructions of thin-walled beams, it is important to have a simple method for estimating the bearing capacity and the potential loss of local and general stability of the structure.

Abstract: Gas turbine is a type of rotary engine that consists of compressor, combustion chamber, and turbine sections. This type of engine works in the Brayton Cycle principle that is compression of atmospheric flow, combustion of air-fuel mixture and expanding high temperature combustion flow to generate power output from turbine. The aim of this study is to determine the duct geometry and flow conditions of the gas turbine blades having the internal cooling ducts that acquire highest heat transfer on turbine blades. For different design of internal duct geometries and flow conditions, Fluent solver is used and solutions are validated with Han’s experimental results.

Abstract: Efforts have been given to improve the turbine blades ability to withstand high temperature for a long period of time by implementing effective cooling system. There are many aspects that should be considered when implementing impingement cooling. This paper will only cover two trending aspects in impingement cooling implementation; the jet-to-target plate distance and the application of ribs in promoting better impingement cooling performance. For target plate distance to impingement jet diameter value, H/d > 1, the area-averaged Nusselt number also decreases as the H/d value increases. This may have been due to a reduction of the amount of momentum exerted by the impinging jets onto the target plate. For H/d < 1, the results have been proven otherwise. Heat transfer in impingement/effusion cooling system in crossflow with rib turbulators showed higher heat transfer rate than that of a surface without ribs because the ribs prevent the wall jets from being swept away by the crossflow and increase local turbulence of the flow near the surface. It could be concluded that both H/d ratio and ribs installation play an important role in enhancing impingement cooling systems heat transfer effectiveness.

Abstract: Based on the geometric and kinematic relationship between the spiral guide rollers rib and the grinding wheel in the rib grinding with the special machine, the ribs shape surface after grinding was analysised, and the equations for the ground rib axial profile were established. Numerical analysis was conducted in an example, and the results show that the ground rib axial profile is approximately linear in most region, but seriously nonlinear in the root region of about 0.5mm height, and the profile inclination direction changes when the vertical angle of grinding wheel head is less than a value which is slightly less than the helix angle of the guide roller.

Abstract: The goal of this study is to determine the optimum value of design variables in mixed conditions of the thickness, height and draft angle of reinforcing ribs within an objective limit in ABS resin and a high glossy surface. For this purpose, we investigated the actual depths of sink marks on the surface of the specimen that was manufactured with an injection mold specifically for this study. A response surface methodology with the Box-Behnken design was used to analyze the real depths with combinations of the thickness, height and draft angle of the ribs. The result shows that the most influential factor to increase the shrinkage is the thickness of ribs and that the optimum value of the rib thickness is a multiple of 0.31 of the section thickness. It was found that the rib height and rib draft angle are not factors that can change the sink amount.