A Parametric Study on Particulate Al-SiC Composite Bolted Joints

Author(s):  
Samir N. Shoukry ◽  
Jacky C. Prucz ◽  
Gergis W. William

The main objective of this study is to predict theoretically the stress distributions around the holes in a bolted joint made of particulate metal matrix composite and to investigate the associated load transfer efficiencies both for a single and double lap bolted joints. A three-dimensional finite element parametric model has been developed to examine the effects of various design parameters on the structural performance of such joints. The main feature of this model is explicit modeling of the sliding interfaces between the connected plates and the washers, and those between the hole and the bolt. The model response showed an excellent agreement with a closed form solution as well as experimental data. The results indicated that unsymmetric configuration of single lap joints causes bending as the load is applied, which is opposite of the double lap joints. This research quantifies the relationship between the stress developed around the hole and washer diameter, tightening pressure, and clearance between the bolt and hole. It was also observed that variations in Young's modulus have no significant effect on the stress concentration around the hole.

2010 ◽  
Vol 118-120 ◽  
pp. 147-150
Author(s):  
Da Zhao Yu ◽  
Yue Liang Chen ◽  
Yong Gao ◽  
Wen Lin Liu ◽  
Zhong Hu Jia

Three-dimensional finite element model of a cracked bolted joint has been developed in the non-linear finite element code MSC.Marc and attempts were made to validate it by comparing results with those of experiments and other finite element. Issues in modeling the contact between the joint parts, which affect the accuracy and efficiency of the model, were presented. Experimental measurements of load transfer were compared with results from finite element analysis. The results show that three-dimensional finite element model of cracked bolted joint can produce results in close agreement with experiment. Three-dimensional effects such as bolt titling, seconding and through-thickness variations in stress and strain are well represented by such models. Three-dimensional finite element analysis was also used to study the effects of hole mod and crack on the load transfer behaviour of single lap bolted joints. The results show that hole mode has big effect on load transfer of cracked bolted joint. In the whole progress of crack growth, the load transfer through bolt 1 decrease, and almost all of the load duduction of bolt 1 transfer into blot 2 rather than into bolt 3.


1999 ◽  
Author(s):  
K. Iyer ◽  
C. A. Rubin ◽  
G. T. Hahn

Abstract Three-dimensional finite element analyses (FEA) of an elastic, single rivet-row, aluminum alloy lap joint are presented. The effects of rivet geometry (countersinking), rivet material and interfacial friction coefficient are examined. Interference and lateral clamping are not treated. Panels loaded in tension with vacant, tapered holes are also examined. Load transfer through the joint, the joint compliance, rivet-tilt, the local slips at rivet-panel and panel-panel interfaces, contact pressures and local stresses are evaluated. Relations between these features and the contact and bending driven stress concentration are clarified. The work shows that the stress concentration factor, rivet-panel slips, peak stresses, contact pressures and rivet deformation are all related, and increase with the severity of the countersink. Panel bending, rivet tilt and countersinking introduce large, out-of-plane stress gradients and shift the peak stresses to the interior surface of the countersunk panel. The results demonstrate the importance of out-of-plane distortions in accounting for the behavior of the riveted lap joints. Three opportunities are identified for improving lap joint performance without increasing the weight.


Author(s):  
Chen-Ming Kuo

Some of the design parameters in AASHTO’s Guide for Design of Pavement Structures require experienced engineering judgment to obtain adequate designs. The load transfer parameter for concrete pavements in the AASHTO Guide is reviewed. A set of equations was developed to assist in choosing a J-factor for various pavement conditions. With three-dimensional finite element analysis, factorial runs were conducted to find the relationships between the critical stresses and joint design parameters—that is, joint width, diameter, length, and spacing of dowel bars. Extended procedures that incorporate dowel parameters into the J-factor were proposed. Conclusions were made to clarify the load transfer concept in the current AASHTO Guide and the effects of joint parameters on pavement performance.


2000 ◽  
Vol 123 (4) ◽  
pp. 686-698 ◽  
Author(s):  
K. Iyer ◽  
C. A. Rubin ◽  
G. T. Hahn

Primary fretting fatigue variables such as contact pressure, slip amplitude and bulk cyclic stresses, at and near the contact interface between the rivet shank and panel hole in a single rivet-row, 7075-T6 aluminum alloy lap joint are presented. Three-dimensional finite element analysis is applied to evaluate these and the effects of interference and clamping stresses on the values of the primary variables and other overall measures of fretting damage. Two rivet geometries, non-countersunk and countersunk, are considered. Comparison with previous evaluations of the fretting conditions in similar but two-dimensional connections indicates that out-of-plane movements and attending effects can have a significant impact on the fatigue life of riveted connections. Variations of the cyclic stress range and other proponents of crack initiation are found to peak at distinct locations along the hole-shank interface, making it possible to predict crack initiation locations and design for extended life.


Author(s):  
Hao Gong ◽  
Jianhua Liu ◽  
Xiaoyu Ding

An understanding of conditions that trigger the loosening of bolted joints is essential to ensure joint reliability. In this study, a three-dimensional finite element model of a typical bolted joint is developed, and a new simulation method is proposed to quantitatively identify the critical transverse force for initiating loosening. This force is used to evaluate the anti-loosening capacity of bolted joints. Using the proposed simulation method, the effects of factors affecting critical loosening are systematically studied. It is found that the preload, frictional coefficients at the thread and the bearing surfaces, clamped length, and fit tolerance mainly affected loosening. When the preload and friction coefficients are increased, and the clamped length and fit tolerance are reduced, loosening is inhibited. Experiments are performed to demonstrate the reliability of the results. Finally, a suggestion is proposed to improve the design guideline VDI 2230 for bolted joints, which considers the requirement of avoiding loosening under vibrational loading.


2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840083 ◽  
Author(s):  
Xuetong Liu ◽  
Jianhua Liu ◽  
Huajiang Ouyang ◽  
Zhenbing Cai ◽  
Jinfang Peng ◽  
...  

The dynamic response of bolted joints subjected to torsional excitation is investigated experimentally and numerically. First, the effects of the initial preload and the angular amplitude on axial force loss of the bolt were studied. Second, the change of hysteresis loops with the increasing number of loading cycles was found under a larger torsional angle. At last, a fine-meshed three-dimensional finite element model was built to simulate the bolted joint under torsional excitation, from which the hysteresis loops were obtained under varying angular amplitudes. The results of numerical analysis are in good agreement with those of experiments.


Author(s):  
C-P Fung ◽  
J Smart

Countersunk and snap riveted single lap joints have been examined both experimentally and numerically. A total of 11 specimens were fatigued to failure with failures occurring in either the plate or the rive***r. The failures have been metallurgically examined to determine the cause of failure. The joints have also been analysed using the finite element method. Initially a single lap joint has been modelled as a ‘stepped plate’ and the results for the stress concentration factor found to be in reasonable agreement with published data. However, the stress concentration for this joint occurred at a point away from the point of failure of a riveted joint. A fuller three-dimensional finite element model has been constructed and the stress patterns around the rivet determined. These stress patterns are discussed in relation to the results from the metallurgical examination.


Author(s):  
Liang Cheng ◽  
Qing Wang ◽  
Yinglin Ke

In order to investigate the effect of shim compensation for nonuniform gaps in aircraft assembly, the influence of the shims with different material and parameters on bolted joints is studied in this paper. According to the real material and assembly conditions of the aircraft joint structures, the specimen and experiment are designed to obtain the tensile performance of the joint structures with different shims. A three-dimensional finite element model, which incorporates the Johnson–Cook material property of the alloys, traction-separation law of liquid shims, contact relationships between the joint elements, and boundary conditions of the tensile process, is established with the specimen configurations. After validating through comparing with the experimental results, the modeling method is adopted to simulate the tensile response of the bolted joints with shims. Furthermore, both the influence of the shim material and thickness on the mechanical behaviors of bolted joints is investigated in detail. Shims can considerably reduce the assembly stress of joint structures and improve the joint stiffness and load capacity, and this effect is more remarkable with the increase of gap values. Liquid shims improve the joint stiffness due to its cohesive ability, while solid shims improve the joint load capacity. Hybrid shims possess a composite shimming effect of liquid and solid shims. Whatever the shim material is applied, the joint stiffness and strength drop with the growth of shim thickness, so strict deviation control method should be taken to ensure the assembly gaps as small as possible. The research results enhance the knowledge of shimming effect on joint structures, and thus offer positive guidance for practical application in aircraft assembly.


Author(s):  
William G. Davids ◽  
Zongmu Wang ◽  
George Turkiyyah ◽  
Joe P. Mahoney ◽  
David Bush

The features and concepts underlying EverFE2.2, a freely available three-dimensional finite element program for the analysis of jointed plain concrete pavements, are detailed. The functionality of EverFE has been greatly extended since its original release: multiple tied slab or shoulder units can be modeled, dowel misalignment or mislocation can be specified per dowel, nonlinear thermal or shrinkage gradients can be treated, and nonlinear horizontal shear stress transfer between the slabs and base can be simulated. Improvements have been made to the user interface, including easier load creation, user-specified mesh refinement, and expanded visualization capabilities. These new features are detailed, and the concepts behind the implementation of EverFE2.2 are explained. In addition, the results of two parametric studies are reported. The first study considers the effects of dowel locking and slab-base shear transfer and demonstrates that these factors can significantly affect the stresses in slabs subjected to both uniform shrinkage and thermal gradients. The second study examines transverse joint mislocation and dowel looseness on joint load transfer. As expected, joint load transfer is greatly reduced by dowel looseness. However, while transverse joint mislocation can significantly reduce peak dowel shears, it has relatively little effect on total load transferred across the joint for the models considered.


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