Analysis of influence factors of rail corrugation in small radius curve track

In order to effectively prevent and control the generation and development of rail corrugation, according to the actual line condition of the small radius curve section, the vehicle (with flexible wheel sets)–track space coupled model was established by using the multi-body dynamic software UM (Universal Mechanism), which could consider the coupled relationship in three directions of space, and the dynamic analysis for the corrugation section was carried out by using the model. Then, based on the theory of friction self-excited vibration, the three-dimensional model of a wheel–rail system was established by using the finite-element software ABAQUS, and the complex eigenvalue analysis of influence factors of rail corrugation was conducted based on wheel–rail contact parameters obtained by dynamic calculation. Through the stability analysis of the wheel–rail system with different fastener vertical and lateral stiffnesses, friction coefficients, and superelevation states, we find that properly increasing the fastener vertical and lateral stiffnesses, controlling the wheel–rail friction coefficient below 0.4, and keeping the balanced superelevation state of the track structure can effectively reduce the occurrence possibility of unstable vibration of the wheel–rail system, thus inhibiting the generation and development of rail corrugation. The excess superelevation state of the track structure results in the unstable friction self-excited vibration of the wheel–rail system at the inner wheel–inner rail, while the deficient superelevation state results in the unstable friction self-excited vibration of the wheel–rail system at the outer wheel–outer rail, which shows that the superelevation state of the track structure directly affects the formation of rail corrugation and determines the development order of corrugation of inner and outer rails. This conclusion can well explain the cause of corrugation appearing on only one side rail.

Structural Optimization of Truck Front-Frame Under Multiple Load Cases

An optimization framework is developed to minimize structural weight of the front-frame of heavy-duty trucks while satisfying stress constraint. The shape of the frame is defined by a number of design parameters (which define the shape of the side-rail, position and width of the internal brackets, and width of the flanges). In addition, the thickness of the engine-mount, the side-rails, inner-brackets, radiator mount, shock absorber and cab-mount connector are also considered as design variables. Aluminum Alloy, 6013-T6 is chosen as the material and the maximum allowable stress is the yield stress (320 MPa). A quantity known as ‘Violation’ is defined as the ratio of area in the front-end module where stress constraint is violated to the total area of the frame is introduced to implement stress constraints. For optimization, the penalty method is used where the objective is to minimize the total weight while keeping the value of the ‘Violation’ parameter less than 0.1 %. The Particle Swarm Optimization Algorithm is implemented using parallel computation for optimizing the structure. Commercial FEA software MSC.PATRAN is used for creating the geometry and the mesh whereas MSC.NASTRAN is used to perform static analysis. Six design load conditions, each corresponding to a road condition are used for the problem.

Load-carrying capacity and the size of chair joints determined for users with a higher body weight

Market globalization, with its accompanying higher living standards, food availability, and sedentary jobs noticeably affects the eating habits and lifestyles of people. Therefore, the body weight of populations is increasing globally. These changes must be taken into account when various everyday items (furniture, clothes, and shoes) are designed. Population-based studies dealing with measuring the height and body weight of adult male populations were analyzed (body mass index categories: 25 kg/m2 to < 30 kg/m2 (overweight), > 30 kg/m2 (obese), > 35 kg/m2 (severely obese)). Because of the analysis of anthropometric parameters in Central Europe, especially Slovakia, it is necessary to produce chairs with two weight categories for the common population (normal weight up to 110 kg) and a population with a higher weight. The aim of this research was to investigate the effect of the body weight of users on the load capacity and dimensions of structural elements of chairs. Following the static analysis of the load-carrying capacity of several chair types, it was calculated that the only suitable construction type for users with a higher weight is the construction with stretchers. The cross-section of the leg space and side rail increased by 20% and 25%, respectively, in the case of a 150-kg user and tenon dimensions of 10 mm × 60 mm × 30 mm.

PERANCANGAN DAN PEMBUATAN SILICON SPRAYER PADA ROBOT ABB IRB 4600 MESIN PLASTIK INJEKSI HWA CHIN 1060-3 DI PT API

PT API merupakan salah satu perusahaan yang bergerak dibidang plastik injeksi untuk industri otomotif roda empat (4W). Pada proses produksi PT API menggunakan robot ABB IRB 4600 yang digunakan untuk mengambil part spacer side rail FR RH/LH yang berbahan baku material PP cosmoplene AZ 564 G dari dalam mesin plastik injeksi Hwa chin1060-3 dengan berat mesin 1060 ton. Pada proses pengambilan part spacer side rail FR RH/LH dari mold memerlukan perlakuan khusus pada saat memproduksinya yaitu dengan cara menyemprotkan cairan silikon di Mold setiap kali proses produksi dilakukan. Tujuan disemprotkannya silikon adalah untuk menghindari part spacer side rail FR RH/LH menempel pada mold. Oleh karena itu ketika pengambilan part dilakukan dengan robot ABB IRB 4600, maka robot harus menyemprotkan silikon ke mold. Untuk mengatasi hal ini dibuatlah silicon sprayer pada robot ABB IRB 4600, agar proses penyemprotan silikon pada saat produksi part spacer side rail FR RH/LH di mesin Hwa chin 1060-3 dapat dilakukan. Hasilnya part spacer side rail FR RH/LH tidak menempel pada mold,ketika pengambilan part dilakukan oleh robot ABB IRB 4600.Kata kunci: Robot, silicon sprayer, part spacer side rail FR RH/LH

Falling Body Impact Behavior of Fiberglass Stepladders With Plastic Knee Braces

According to estimates reported in the U.S. Consumer Product Safety Commission’s National Electronic Injury Surveillance System, there were greater than 10,000 stepladder related injuries treated in hospital emergency rooms nationwide per year in the period from 2009 through 2013. Research and experience have sought to correlate specific stepladder damage patterns to the causes of some injuries involving stepladders. Prior studies have associated a specific damage pattern — inward deformation of the stepladder’s front side rails — with impact loading of a user’s body onto the lower portion of a front side rail following a fall from the stepladder. Those prior studies were conducted using stepladders with metal knee braces and with the ladder cap simply supported during impact testing. Currently sold fiberglass stepladders often have plastic rather than metal knee braces. In our study, side rail impact testing was performed in order to evaluate how a design change from metal knee braces to plastic knee braces affects impact damage patterns in fiberglass stepladders. Biomechanics simulations were used to inform the selection of the weights used for impact testing and allowed the test results to be evaluated in the context of potential body contact scenarios that could produce equivalent loading of the side rail. Our study demonstrates that depending on the weight of the impacting body, fiberglass ladders with plastic knee braces show different dynamic responses to impact loading than do their metal counterparts. Additionally, the test methods in this study incorporate realistic dynamics in that the weight impacted the lower portion of the stepladder’s front side rail while the stepladder was actively tipping with only two of its feet in contact with the ground and with the top cap unsupported. The results indicate that ladders with metal knee braces can permanently deform when impacted with loads less than that required to permanently deform the ladders tested with plastic knee braces. The absence of permanent side rail deformation in the plastic knee braced stepladders tested even after undergoing significant elastic deformation during testing gives rise to new questions about the potential for damage that is not observable based on a visual examination.

Turbine Blade Tip Film-Cooling and Heat Transfer Measurements at High Blowing Ratios

Film-cooling and heat transfer characteristics of a gas turbine blade tip with a suction side rail was investigated in a stationary 3-blade rectilinear cascade. Mounted at the end of a blow-down facility the cascade operated at inlet and exit Mach numbers of 0.29 and 0.75, respectively. The rail was marginally offset from the suction side edge of the tip and extended from the leading to the trailing edge. A total of 17 film-cooling holes were placed along the near-tip pressure side surface and 3 on the near-tip leading edge surface with the objective of providing coolant to the tip. The tip surface itself did not carry any film-cooling holes. Relatively high blowing ratios of 2.0, 3.0, 4.0, and 4.5 and three tip gaps of 0.87%, 1.6%, and 2.3% of blade span made up the test matrix. Pressure sensitive paint (PSP) and Thermo-Chromic Liquid Crystal (TLC) were the experimental techniques employed to measure film-cooling effectiveness and heat transfer coefficient, respectively. Results indicated that when the tip gap was increased, film-cooling effectiveness on the tip surface decreased and heat transfer to the tip surface increased. On the other hand, when the blowing ratio was increased, film effectiveness increased but the effect on heat transfer coefficient was relatively small. The highest heat transfer coefficient levels were found atop the suction side rail, especially in the downstream two-thirds of its length whereas the lowest levels were found on the tip floor in the widest section of the blade.