Effect of Interference on the Mechanics of Load Transfer in Aircraft Fuselage Lap Joints

2006 ◽  
Vol 129 (3) ◽  
pp. 356-366 ◽  
Author(s):  
Amarendra Atre ◽  
W. S. Johnson
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Stress Distribution ◽  
Fatigue Damage ◽  
Structural Integrity ◽  
Crack Nucleation ◽  
Process Variations ◽  
Lap Joints ◽  
Multiaxial Fatigue ◽  
Lap Joint

Much of the fatigue damage in aircraft structures can be linked to the stress concentration arising at the rivet/skin interface in fuselage lap-joints. Fatigue damage can degrade the strength of the structure and reduce structural integrity. The stress distribution around the rivet holes, which depends on several loading conditions, is therefore of prime importance. Critical manufacturing process variations must be taken into account to observe the effect on local stresses at the hole. This paper presents three-dimensional (3D) nonlinear finite element analyses to investigate the stress state at rivet holes in fuselage lap joints. Initially, a 3D single rivet model of the riveting process was developed to characterize the unsymmetric residual stress distribution resulting from rivet installation. Then a global three-rivet model of the fuselage lap-joint, which takes into account the residual stresses from rivet installation and fuselage pressurization, was analyzed and compared to observations available from teardown inspection. The models were then implemented to observe the effects of rivet interference, sealant, and drill shavings on the stress state. A multiaxial fatigue criterion was implemented to predict cycles to crack nucleation for the modeled parameters. The effect of underdriven rivets and sealant were observed to be the most critical on the stress state of the fuselage splice. Excellent comparison with the damage characterization of the fuselage lap-joint provides validation to the finite element model.

A Finite-Element and Experimental Analysis of Stress Distribution in Various Shear Tests for Solder Joints

1998 ◽  
Vol 120 (1) ◽  
pp. 106-113 ◽  
Author(s):  
T. Reinikainen ◽  
M. Poech ◽  
M. Krumm ◽  
J. Kivilahti
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Low Cycle Fatigue ◽  
Material Model ◽  
Lap Joints ◽  
Optical Measurements ◽  
Nonlinear Material ◽  
Lap Joint ◽  
The Finite Element Method ◽  
Shear Tests

Solder alloys are commonly tested with shear tests to study their mechanical properties or low-cycle fatigue performance. In this work, the suitability of various shear tests for quantitative solder-joint testing is investigated by means of the finite element method. The stress state and stress distribution in the following well known geometries are studied: the double-lap test, the ring and plug test, the losipescu test, and two single-lap tests. A new test geometry, the grooved-lap test, is introduced and compared to the conventional tests. The results of simulations with an elastic material model in plane-strain indicate that considerable differences in the purity of the state of shear (rε = −ε1/ε3) as well as in the stress distribution in the joint exist among the shear tests. However, simulations with a nonlinear material model show that stress inhomogenities are smoothed by the plastic and creep deformation occurring in the joint. Optical measurements of the deformation of real single-lap and grooved-lap joints show that the single-lap joint rotates slightly during creep, whereas in the grooved-lap joint no rotation can be detected. This confirms the simulation results that in the single-lap test the initially nonuniform stress distribution changes during creep, and in the grooved-lap test the uniform stress distribution remains constant through the test.

Stress in Bonded Adherends for Single Lap Joints

1996 ◽  
Vol 12 (03) ◽  
pp. 167-171
Author(s):  
G. Bezine ◽  
A. Roy ◽  
A. Vinet
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Numerical Model ◽  
Stress Distribution ◽  
Normal Stress ◽  
Lap Joints ◽  
Axial Loads ◽  
Normal Stress Distribution ◽  
Single Lap Joints ◽  
Element Technique

A finite-element technique is used to predict the shear stress and normal stress distribution in adherends for polycarbonate/polycarbonate single lap joints subjected to axial loads. Numerical and photoelastic results are compared so that a validation of the numerical model is obtained. The influences on stresses of the overlap length and the shape of the adherends are studied.

Random Loads Fatigue: The Use of Spectral Methods Within Multibody Simulation

2005 ◽  
Author(s):  
Claudio Braccesi ◽  
Filippo Cianetti ◽  
Luca Landi
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Dynamic Simulation ◽  
Fatigue Damage ◽  
Spectral Methods ◽  
Mechanical Systems ◽  
Frequency Domain Method ◽  
Stress And Strain ◽  
Damage Evaluation ◽  
Multibody Dynamic

The evaluation of the fatigue damage performed by using the Power Spectral Density function (PSD) of stress and strain state is proving to be extremely accurate for a family of random processes characterized by the property of being stationary. The present work’s original contribution is the definition of a methodology which extracts stress and strain PSD matrices from components modelled using a modal approach (starting from a finite element modelling and analysis) within mechanical systems modelled using multibody dynamic simulation and subject to a generic random load (i.e. multiple-input, with partially correlated inputs). This capability extends the actual stress evaluation scenario (principally characterised by the use of finite element analysis approach) to the multibody dynamic simulation environment, more powerful and useful to simulate complex mechanical systems (i.e. railway, automotive, aircraft and aerospace systems). As regards the fatigue damage evaluation, a synthesis approach to evaluate an equivalent stress state expressed in terms of the PSD function of Preumont’s “equivalent von Mises stress (EVMS)”, starting from the complete stress state representation expressed in terms of PSD stress matrix and easily usable in the consolidated spectral methods, is proposed. This approach allows and has allowed the use of the above methods such as the Dirlik formula as a damage evaluation method. An additional result is the conception and implementation of a frequency domain method for the component’s most probable state of stress, allowing quickly identification of the most stressed and damageble locations. The described methodologies were developed and embedded into commercial simulation codes and verified by using as a test case a simple reference multibody model with a simple flexible component.

Modal Velocity-Based Multiaxial Fatigue Damage Evaluation Using Simplified Finite Element Models

2020 ◽  
Vol 87 (11) ◽  
Author(s):  
Kurthan Kersch ◽  
Elmar Woschke
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Multiaxial Fatigue ◽  
Finite Element Models ◽  
Damage Evaluation ◽  
Geometric Factors ◽  
The Relationship ◽  
General Method

Abstract This work proposes a new method for the fatigue damage evaluation of vibrational loads, based on preceding investigations on the relationship between stresses and modal velocities. As a first step, the influence of the geometry on the particular relationship is studied. Therefore, an analytic expression for Euler Bernoulli beams with a non-constant cross section is derived. Afterward, a general method for obtaining geometric factors from finite element (FE) models is proposed. In order to ensure a fast fatigue damage evaluation, strongly simplified FE-models are used for the determination of both factors and measurement locations. The entire method is demonstrated on three mechanical structures and indicates a better compromise between effort and accuracy than existing methods. For all examples, the usage of velocities and geometric factors obtained from simplified FE models enables a sufficient fatigue damage calculation.

Analysis of the Influence of Mechanical Properties on the Residual Stress in Offshore Chain Links Using the Finite Element Method

2003 ◽  
Author(s):  
Pedro M. Calas Lopes Pacheco ◽  
Paulo Pedro Kenedi ◽  
Jorge Carlos Ferreira Jorge ◽  
Augusto M. Coelho de Paiva
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Structural Integrity ◽  
Critical Crack ◽  
Critical Crack Length ◽  
Mechanical Component ◽  
Operational Life ◽  
Chain Links

Production offshore units have a relative long operational life (about 20 years), during which are submitted to the ocean adverse environment loading produced by the combination of wind, waves and currents. This complex loading history can promote the nucleation and propagation of cracks in mooring line components. The presence of defects establishes a critical situation that can lead to catastrophic failures. In spite of residual stress plays a preponderant part in the structural integrity of a mechanical component, the presence of residual stress is not considered in traditional design of these mechanical components. Therefore, is fundamental to develop new and more precise methodologies for assessing the structural integrity of mooring components. The present contribution regards on modeling and simulation of the residual stress distributions in studless chain links using a tri-dimensional elastoplastic finite element model with large displacements. In the analysis three material conditions, associated with different mechanical properties, were considered. The results indicate that the presence of residual stresses modify significantly the stress distribution in the component. Also, residual stress distribution depends on the mechanical properties of the chain link material. The structural integrity of the mechanical component was studied using the concept of critical volume associated to the material volume susceptible to a certain critical crack size. This methodology permits the evaluation of the critical crack length distribution related to brittle fracture of the component.

Effect of Interference-Fit on Fatigue Life for Composite Lap Joints

2014 ◽  
Vol 939 ◽  
pp. 39-46 ◽  
Author(s):  
Hong Qian Xue ◽  
Qian Tao ◽  
Emin Bayraktar
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Finite Element Simulations ◽  
Cyclic Loads ◽  
Lap Joint ◽  
Interference Fit ◽  
3D Finite Element ◽  
Double Shear

The aim of this study is to examine the effect of the clearance and interference-fit on the fatigue life of composite lap joints in double shear, 3D finite element simulations have been performed to obtain stress (or strain) distributions around the hole due to interference fit using FEM package, Non-linear contact analyses are performed to examine the effects of the clearance and interference for titanium and composite lap joint. Fatigue tests were conducted for the titanium and composite lap joints with clearance fit and interference fit with 0.5, 1, and 1.5% nominal interference fit levels at different cyclic loads. The results shows that interference fit increases fatigue life compared to clearance fit specimens, the titanium and composite lap joint with 1% interference fit level has the better fatigue life.

Distortion Prediction of Welded Thin Plate Lap Joints by Finite Element Analysis and Experiment

2019 ◽  
Vol 796 ◽  
pp. 175-182
Author(s):  
Mohamad Nizam Ayof ◽  
Ruzaini Mohd Nawi ◽  
Nur Izan Syahriah Hussein ◽  
Nor Zulaikha Zainol
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Gas Metal Arc Welding ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Lap Joints ◽  
Lap Joint ◽  
Element Analysis ◽  
Metal Arc Welding

Welding process is an efficient joining process of metals that is achieved by gas metal arc welding (GMAW) process. Localized heating during welding process can result in distortion of the welded plate. The estimation of magnitude and distribution of distortion are important to maintain the quality of products. Finite element method is implemented to investigate the distortions behavior of thin steel plate, cold rolled (SPCC) material in lap joint using GMAW process. A three-dimensional, two-step thermomechanical finite element model study was applied to analyze and evaluate distortion behavior in lap joint. The result of distortion from finite element analysis (FEA) was compared to experimental data to validate the accuracy of the method.

Selective Use of Rubber Toughening to Optimize Lap-Joint Strength

1999 ◽  
Author(s):  
Erol Sancaktar ◽  
Sumeet Kumar
Keyword(s):  
Finite Element ◽  
Joint Strength ◽  
Lap Joints ◽  
Finite Element Models ◽  
Lap Joint ◽  
Bulk Properties ◽  
Rubber Toughening ◽  
Novel Approach ◽  
Rubber Toughened ◽  
Third Stage

Abstract This paper introduces a novel approach to increasing the lap joint strength, different than the traditional methods of either increasing the lap joint area or changing the joint geometry. This is accomplished by the selective use of rubber toughening in epoxy to optimize lap joint strength. This was accomplished in three stages, in the first stage an adduct was prepared, this was used to make bulk tensile specimens to calculate the bulk properties for various concentrations of rubber, i.e. 0, 10 & 20 parts per hundred parts of resin (epoxy). In the second stage finite element models were developed using the bulk properties previously obtained. Interfacial stresses were used to access the trends obtained by the selective use of rubber toughening at different location of the overlap in different configurations. The modeling of adhesive joints was done using ALGOR 2-D, linear and nonlinear Finite Element Analyses (FEA). In the third stage, conducting tensile shear tests on the lap joints validated the trends from the finite element models. Finite element modeling and meshing of the lap joints having 25.4 mm and 50.8 mm adhesive overlap lengths were completed. Different configurations of rubber toughened and untoughened adhesive were tried in these two overlaps. The validation was done by tensile lap joint tests conducted on an Instron mechanical tester coupled with an extensometer. Comparable strengths were obtained for completely toughened overlap and the configuration where only the edges of the adhesive overlap were toughened and the region in-between was untoughened. Also, the nonlinear FEA was shown to represent the experimental results more closely than the linear approach.

Numerical Analysis of the Stress in Joggle Double Lap Joint

2012 ◽  
Vol 511 ◽  
pp. 150-153
Author(s):  
Xiao Ling Zheng ◽  
Ling Wu ◽  
Min You ◽  
Kai Liu ◽  
Cun Jun Chen
Keyword(s):  
Stress Distribution ◽  
Equivalent Stress ◽  
Peak Stress ◽  
Middle Part ◽  
Lap Joints ◽  
Lap Joint ◽  
The Finite Element Method ◽  
Adhesively Bonded ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Both normal and joggle double lap joints were numerical analyzed to get the stress distribution in mid-bondline and in adherends near the interface using the finite element method (FEM). The results from the numerical simulation show that nearly all the peak values of the stress components as well as the von Mises equivalent stress distributed in both mid-bondline and adherend near the interface of the adhesively bonded joggle double lap joint are significantly decreased to the normal one. It was pointed out that the load bearing capacity of the joggle double lap joint may be higher than that of the double lap joint for its decrease of peak stress, much evenly stress distribution in the middle part of the overlap zone so that more load can be subjected by the joggle double lap joint.

scholarly journals 2-D Strength Prediction of Single-row Multi-bolted Joints Woven Fabric Kenaf Composites

2018 ◽  
Vol 7 (3.7) ◽  
pp. 21 ◽  
Author(s):  
Khairi Supar ◽  
Hilton Hilton Ahmad
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Lap Joints ◽  
Bolted Joints ◽  
Woven Fabric ◽  
Single Row ◽  
Specific Strength ◽  
Bearing Stress ◽  
Kenaf Composites ◽  
Kenaf Fibers

Implementation of multi-bolts arrangements in structures connections are commonplace in steel design to allow for joint efficiency and stronger connections. Woven fabric kenaf fibers are potentially used as reinforcement in composite materials due to excellent specific strength, renewability and less hazardous during handling as compared to commercial fibers. A two-dimensional Extended Finite Element Method (XFEM) framework of single-row multi-bolted joints has been developed to study the stress distribution and predict the joint bearing stress at failure. Stress distribution among adjacent bolts were compared along the hole boundary and net-tension plane, suggesting net-tension failure occurred at end-bolt. The predicted bearing strength from finite element modelling are validated against experimental framework. The testing series under investigated consists of four datasets from single-row 2 bolts and 3 bolts single-lap joints.  Current study showed that the XFEM models demonstrated good agreements with the experimental results.  

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