The process of interference fit and Bolt clamping force are two effective techniques for improving the fatigue life of the joints and are used in various industries, especially in aerospace and automotive. Most of the previous studies have investigated separate effects of the interference fit and Bolt clamping force on the fatigue life of the specimens. In the present research fatigue behavior of interference fitted specimens combined with Bolt clamping force has been investigated yet. On the other hand, the pervious researches on the interference fit and Bolt clamping force have been studied at laboratory temperature and the effect of temperature changes has not been investigated. To investigate the effect of temperature on the fatigue life of specimens, two different temperatures (i. e. 60° C and 120° C), aside from room temperature, were selected and fatigue life of specimens are studid at these tempratures. The fatigue tests were performed on the specimens of Al-alloy 7075-T6 alloy to obtain S-N data.

In this paper the change in clamping force (preload) value has been investigated in Bolted joints under tensile axial load both experimentally and numerically. To do this, a holed plate of Al-Alloy 7075-T6 is clamped at its hole by a Bolt and nut, and then the plate is subjected to a tensile axial load. In order to evaluate the Bolt clamp force magnitudes due to the applied torque to the nut, an experimental method has been used by measuring the compressive axial stress from the axial strain of a steel bush that was located between the nut and the plate. The investigation was carried out on two specimens that were clamped by two different torques. In each specimen the clamp force was measured at first and then its changes were recorded during the axial tensile load that was applied to the plate ends. In the numerical part, 3-D finite element models were used to simulate the Bolt clamping process and the changes in clamping force when the plate is subjected to the tensile axial load. Both experimental and numerical methods show that the clamping force is reduced during tensile axial load application. This is due to the transverse plate contraction that causes the clamp to relax. The percentage of clamping force reduction is more pronounced at the joint where bigger torque was applied to the nut.

The electrical resistance between the different components of fuel cell, related to the compressive stress between the various components is the fuel cell. In this study, two important goals pursued: first obtain the least stress on the gaskets for leakage will not happen and additional investigated the effect of stress distribution on gas diffusion layer on the amount of electrical resistance. To reach this goal, first designed experimental setup and achieved 2MPa minimum compressive stress on the gasket to prevent leakage. Then by another experimental setup effect of compressive stress on resistance value between the different parts have been investigated. Then according to experimental data, effect of clamping force on electrical resistance in simulation was investigated. Moreover effective parameters on pressure distribution on gas diffusion layer and electrical resistance was investigated. It was observed that the electrical resistance decreases by increasing clamping force. also observed pressure distribution in 4 Bolt not uniform. By increasing Bolt up to 8 the pressure uniformity was better than 4 Bolt. But by increasing the number of Bolt 8 to 12 significant changes not occurred.

This paper presents the results of the assembly process of a gasketed Bolted flanged pipe joint for two different Bolt tightening strategies, i.e. ASME and Industrial using torque control of preload method. The final clamping force is achieved in four and five passes in ASME and Industrial strategy respectively. Axial Bolt stress variation, at the end of each pass, individual Bolt bending behavior, gasket stress and flange stress variations for both strategies are discussed.

In this research, why and how of fatigue crack initiation and propagation of aluminum alloy 7075-T6 double lap Bolted joint were investigated and analyzed numerically. The joint includes three AI-alloy plates with a single Bolt fastener, which was subjected to cyclic loads. In this investigation, finite element methods were applied to model of the joint in order to determine the stress and stain distributions at the joint. The obtained results were validated by previous experimental fatigue test and fractography results. In the numerical analysis, the stress and strain distributions were calculated due to the Bolt clamping force followed by an axial load applied to the joint. The Fractography of specimens shows two kinds of fatigue modes: a bearing mode at the joint hole at low clamping forces and a fretting mode on the plate surface at high ones. In the present paper, these two modes of fatigue were expounded by numerical (FE) results.

An efficient work holding plan must include an optimized clamping scheme. This article uses finite element analysis with a supportive combination of neural network and genetic algorithm to compute an optimized set of clamping forces. A frictional finite element model of work part-fixture system under cutting and clamping forces is solved. The results are utilized for training and querying an artificial neural network (ANN). The ANN is employed to recognize a pattern between the clamping forces and contact status in the work piece-fixture system and maximum elastic deformation of the work piece. Using this pattern as fitness function, a genetic algorithm based program determines the optimum values of clamping forces. These forces while hold the component securely, would not cause its excessive deformation or stress. Therefore they can be prescribed confidently for process planning. The advantage of this work against similar studies is manifestation of the state of contact between fixture elements and work part. The study facilitates fixture design task in a design for manufacture environment and contributes to computer aided process planning.

In this research, the effects of torque tightening on the stress distribution in double lap simple Bolted and hybrid (Bolted-bonded) joints have been investigated numerically. In order to determine the Bolt clamping force value due to tightening torque in simple Bolted and hybrid joints, which is necessary in numerical simulation, an experimental approach has been proposed. To do so, two kinds of joints, i.e. double lap simple and hybrid joints were prepared. To determine the Bolt clamping force or pretension resulting from the torque tightening, at different applied torques, for both kinds of joints a special experimental method was designed using a steel hollow cylinder that was placed between the nut and the plate. In order to obtain the stress distribution in the joint plates for both kinds of the joints, with two different amounts of tightening torque, three-dimensional finite element models were simulated by a general finite element code. The obtained results revealed that the amounts of resultant stresses were reduced by increasing the tightening torque due to compressive stresses. Furthermore, in the hybrid joints, the stress concentration around the hole is reduced significantly. Finally, the comparison of the obtained results, confirms that the hybrid joints have better static strength than simple joints for all levels of the tightening torque.