Celalettin Yuce

The Investigation of Stress Distribution on the Tractor Clutch Finger Mechanism by Using Finite Element Method

In recent years, there has been an increasing demand for tractor usage for agricultural activities in the world. Tractors are an integral part of mechanization and have a crucial role to play to enhance agricultural productivity. They are used for many kinds of farm work, under various soil and field conditions. It provides agricultural activities in challenging conditions by using several farming equipment. During the operations, tractors have to efficiently transfer power from the engine to the drive wheels and PTO through a transmission. Tractor clutch is the essential element in this system. During the torque transmission, loads which occur on the clutch components cause damages. In many cases, especially PTO clutch finger mechanism is fractured under the torque transmission.In this study, finger mechanism, which used in tractor clutch PTO disc, is investigated. Finite element analyses were performed for two different thicknesses (3.5 and 4 mm) of the finger mechanism. Stress and deformation values which occur during the transfer of power in a safe manner are investigated for these thicknesses. The finger mechanism CAD models were created using CATIA V5 and then imported into ANSYS for static finite element analyses. As a result of the analyses, approximately 13% stress decreasing was observed with the increment of the 0.5 mm for the finger thicknesses. Results from the analyses provide an accurate prediction of the material yielding and load path distribution on the PTO clutch finger. To verify the analyses results prototype PTO finger mechanism was manufactured and was conducted bench tests. Consequently, a good correlation was achieved between finite element model and test results.Copyright

Effect of Rim Thickness on Tooth Root Stress and Mesh Stiffness of Internal Gears

In recent years, internal gears are used commonly in a number of automotive and aerospace applications especially in planetary gear drives. Planetary gears have many advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations. Although internal gears have many advantages, there are not enough studies on it. Designing an internal gear mechanism includes two important parameters. The gear mesh stiffness which is the main excitation source of the system. In this paper, 2D gear models are developed in order to compute gear mesh stiffness for various rim thicknesses and different rim shapes of the internal gear design. Effects of root stress with varying rim thickness and some tooth parameters are investigated by using 2D gear models. The stress calculated according to ISO 6336 and the stresses calculated against FEM are compared. These results are well-matched. It is observed that when the rim thicknesses are increased, both the maximum bending stresses and gear mesh stiffness are decreased considerably.Copyright

Prototyping a New Lightweight Passenger Seat

Profitability is the key concern for transport companies. Costs are increased due to the rising fuel prices and technological investments. As well as new legal restrictions on the emission rates have forced the sector different fuel efficient technologies. Reducing weight is one of the most important methods of improving fuel efficiency and cutting CO2 emissions. Accordingly lighter, more fuel efficient, environmentally sustainable and safety vehicles are in the priority list of European authorities. And also the future of hybrid and electric vehicles depends on the lightweighting. The seat structure was chosen as the area for study which presented the best opportunity for weight reduction by the use of new materials. A seat provides comfort and safety of an occupant’s while travelling. In the event of crash, the passenger seat is exposed many different forces. For this reason it should be designed sufficient strength and stiffness. Therefore an optimized seat design should be aesthetically pleasing, ergonomic, light and meet the safety requirements. Seats play an important role in mass of buses and coaches due to number of seats per vehicle. In this project, finite element analysis, together with topology and free-size optimization is used to design a lightweight passenger seat for new generation commercial vehicles.The seat CAD models were created with CATIA V5 and then imported into HyperMesh for finite element model creation and analysis. Results from the nonlinear analysis provide an accurate prediction of the material yielding and load path distribution on the seat structural frame components. In the end, the verification tests which were determined by ECE are applied the new seat and results were compared with the FEA results.In this study, the lightweight passenger seat prototypes have developed. High strength steel and fiber-reinforced plastic parts are used. An overall 20% weight reduction is achieved including the structural frame, cushion, armrest, and pillar. And also the new passenger seat provides ECE safety norms.Copyright

Effects of Heat Input in Laser Welding of Dissimilar Galvanized Steel to Aluminium Alloy

The hybrid structures of aluminum-steel have been increasingly used for body-in-white constructions in order to reduce weight and cost. Obtaining acceptable joints between steel and aluminum required a better understanding of welding metallurgy and their effects on the resultant mechanical properties as well as the microstructure of the joints. In this research, laser welding of galvanized steel and aluminum alloy in an overlapped configuration was carried out. The influence of heat input on the weld bead dimension, microstructural and mechanical properties of the joints was studied. The experimental results showed that the penetration depth and weld width increased with the increase of heat input level. However, in order to limit IMC layer thickness and hardness at the surface of the weld seam and aluminum alloy, iron to aluminum dilution should be restricted by limiting the penetration depth. At lower heat input levels, less brittle IMC formation was formed. Consequently, with limited penetration depths at low heat input levels, tensile shear load increased, with failures located in the interface of the joints.

An improved numerical method for the mesh stiffness calculation of spur gears with asymmetric teeth on dynamic load analysis

Gears are one of the most crucial parts of power transmission systems in various industrial applications. Recently, there emerged a need to design gear drivers due to the rising performance requirements of various power transmission applications, such as higher load-carrying capacity, higher strength, longer working life, lower cost, and higher velocity. Due to their excellent properties, gears with asymmetric teeth have been designed to obtain better performance in applications. As the rotation speed of the gear transmission increases, the dynamic behavior of the gears has become a subject of growing interest. The most important contributing factor of dynamic behavior is the stiffness of the teeth, which changes constantly throughout the operation. The calculation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. The primary objective of this article is to develop a new approach to calculate gear mesh stiffness for asymmetric gears. With this aim in mind, single tooth stiffness was calculated in the first stage of the study using a finite element method. This study presents crucial results to gear researchers for understanding spur gears with involute asymmetric teeth, and the results will provide researchers with input data for dynamic analysis.

Optimum Design of Tractor Clutch PTO Finger by Using Topology and Shape Optimization

Tractors are one of the most important agricultural machinery in the world. They provide agricultural activities in challenging conditions by using various agricultural machineries which are added on them. Therefore, there has been a rising demand for tractor use for agricultural activities. During the power transmission, tractor clutches are exposed to high static and cyclic loading directly. Thus, most of clutch parts fail before completing their design life which is under 106 cycles. Especially, because of the high stress, there are a number of fractures and breakages are observed around the pin area of the finger mechanisms. Due to these reasons, it is necessary to re-design these fingers by using modern optimization techniques and finite element analysis.This paper presents an approach for analysis and re-designs process of tractor clutch PTO finger. Firstly, the original designs of the PTO fingers are analyzed by using finite element analysis. Static structural analyses are applied on these fingers by using ANSYS static structural module. The boundary conditions are determined according to the data from the axial fatigue test bench. Afterwards, the stress-life based fatigue analyses are performed with respect to Goodman criterion. It is seem that the original design of the PTO finger, failed before the design life. Hence, the PTO finger is completely re-designed by using topology and shape optimization methods. Topology optimization is used to find the optimum material distribution of the PTO fingers. Topology optimization is performed in solidThinking Inspire software. The precise dimensions of the PTO fingers are determined by using shape optimization and response surface methodology. Two different design parameters, which are finger thickness and height, are selected for design of experiment and 15 various cases are analyzed. By using DOE method three different equations are obtained which are maximum stresses, mass, and displacement depending on the selected design parameters. These equations are used in the optimization as objective and constraint equations in MATLAB. The results indicate that the proposed models predict the responses adequately within the limits of the parameters being used. The final dimensions of the fingers are determined after shape optimization. The new designs of the PTO fingers are re-analyzed in terms of static and fatigue analysis. The new design of the PTO finger passed the analysis successfully. As a result of the study, the finger mass is increased 7% but it is quite small. Maximum Equivalent Von-Misses stress reduction of 25.3% is achieved. Fatigue durability of the PTO finger is improved 53.2%. The rigidity is improved up to 27.9% compared to the initial design. The optimal results show that the developed method can be used to design a durable, low manufacturing cost and lightweight clutch parts.Copyright

Design and Analysis of Internal Gears With Different Rim Thickness and Shapes

In recent years, thanks to their significant advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations, internal gears have been used in automotive and aerospace applications especially in planetary gear drives. Although internal gears have a number of advantages, they have not been studied sufficiently. Internal gears are manufactured by pinion type cutters which are nearly identical with pinion gear except the addendum factor which is 1.25 instead of 1. The tip geometry of a pinion type cutter which determines the fillet of internal gear tooth can be sharp or rounded. In this study, the design of internal gears were investigated by using a traditional approach. Mathematical equations of pinion type cutter were obtained by using differential geometry, then the equations of internal gear tooth were derived accurately by using coordinate transformations and relative motion between the pinion type cutter and internal gear blank. A computer program was generated to attain points of internal gear teeth and three dimensional design of complete gear. 20°-20° were used as pressure angle. To find optimum internal gear geometry, different rim thicknesses and shapes are tried out for finite element analyses. There were several parameters that were shown to effect the performance of the internal gears, with tooth stiffness being the most significant parameter. Tooth stiffness was also vitally influence the dynamic analysis. In order to compute gear tooth stiffness of the internal gear with various rim thicknesses and shapes, finite element analysis was used. A static analysis was performed to assess the gear bending stress and tooth displacement. Tetrahedral element type was selected for meshing. The internal gear outer ring was fixed and the force of 2500 N was applied on the tooth. According to the displacement values from the analysis internal gear tooth stiffness were calculated individually. Additionally, the effect of root bending stress with varying rim thickness, shapes, and root radius were investigated. The bending stresses were calculated according to ISO 6336 and using finite element analysis were shown to be in good agreement. It was shown that when the rim thickness and fillet radius were increased, the maximum bending stresses decreased considerably. As rim thickness was increased, the maximum bending stress decreased nearly 23%. It was also shown that as the fillet radius decreased, the maximum bending stress increased, whereas the rim stresses slightly changed. As the fillet radius was decreased, the maximum bending stress increased nearly 10%. It was also observed that when rim thickness was increased, the stress on the rim was decreased, whereas tooth stiffness was increased. However, fillet radius had no visible effect both on rim stress and tooth stiffness. Furthermore, it was shown that the rim shape had significant effect on rim stress.Copyright

Effect of Rotational Speed and Dwell Time on Mechanical Properties of Dissimilar AA1050-AA3105 Friction Stir Spot Welded Joints*

Abstract Friction stir spot welding is a newly developed joining technology which is expected to be used in the automotive industry for joining body parts made of aluminum sheets. The effect of the rotational speed and dwell time on the mechanical properties of dissimilar friction stir spot welded aluminum sheet alloys was investigated in this study. In the experimental studies, macro-structural characterization, micro-hardness tests and tensile shear tests were conducted. The experimental results showed that the tensile shear load and tensile deformation of the friction stir spot welded joints decreased roughly by 20 % and 25 %, respectively, when the rotational speed increased from 1000 rpm to 2000 rpm. On the other hand, when the dwell time increased from 3 s to 11 s, the tensile shear load increased roughly by 7 %, while the tensile deformation decreased roughly by 19 %, respectively.

A Novel Method for Calculation Gear Tooth Stiffness for Dynamic Analysis of Spur Gears With Asymmetric Teeth

Recently, there have been a number of research activities on spur gears with asymmetric teeth. The benefits of asymmetric gears are: higher load capacity, reduced bending and contact stress, lower weight, lower dynamic loads, reduced wear depths on tooth flank, higher reliability, and higher efficiency. Each of the benefits can be obtained through asymmetric teeth designed correctly. Gears operate in several conditions, such as inappropriate lubrication, excessive loads and installation problems. In working conditions, damage can occur in tooth surfaces due to excessive loads and unsuitable operating conditions. One of the important parameters of the tooth is stiffness, which is found to be reduced proportionally to the severity of the defect by asymmetric tooth design as described in this paper. The estimation of gear stiffness is an important parameter for determining loads between the gear teeth when two sets of teeth are in contact. In this paper, a 2-D tooth model is developed for finite elements analysis. A novel formula is derived from finite element results in order to estimate tooth stiffness depending on the tooth number and pressure angle on the drive side. Tooth stiffness for spur gears with asymmetric teeth is calculated and the results were compared with well known equations in literature.Copyright

A Virtual Tool for Wear Simulation of Plastic Gear Pairs

Currently plastic gears are widely used in industry, and not only for lightly loaded applications like household appliances, tools, and toys, but also in the more demanding areas of machinery in automotive applications. However there is a need to investigate important properties such as load capacity, endurance, cost, life, stiffness and wear. Tooth wear is one of the major failure modes in plastic gears just like with steel gears. This paper focuses on the simulation of wear for standard and non-standard gears using an analytical approach. A numerical model for wear prediction of gear pairs is developed. A wear model based on Archard’s equation is employed to predict wear depth. The variation of the contact load generated by the cumulative tooth profile wear is simulated and examined. A MATLAB-based virtual tool is developed to analyze wear behavior of standard and non-standard spur gears depending on various gear parameters. In this paper, this virtual tool is introduced with numerical examples.Copyright