Effect of Prelube, Surface Coating and Substrate Materials on Initial Strength of Adhesive Joints Between Al Alloy and Steels

2011 ◽  
Author(s):  
Fan Zhang ◽  
Hui-Ping Wang ◽  
Christina Hicks ◽  
Blair E. Carlson ◽  
Xin Yang ◽  
...  
Keyword(s):  
Bond Strength ◽  
Substrate Surface ◽  
Dissimilar Materials ◽  
Failure Behavior ◽  
Al Alloy ◽  
Initial Strength ◽  
Automotive Body ◽  
Lap Shear ◽  
Identical Material ◽  
Automotive Production

Growing usage of lightweight materials such as Al and Mg alloys in automotive body manufacture has come to a point that bonding of dissimilar materials is a realistic problem to address. A significant issue related to the bonding of dissimilar materials is that the differences in substrate surface conditions and substrate strengths often lead the bond to fail at strength far less than the bond strength established by adhesive manufacturer for a balanced joint. This research experimentally studied several factors potentially influencing initial strengths and debonding modes of adhesively-bonded Al-steel joints using single lap-shear coupons with comparison to like-substrate joints. Three commonly-used SLS coupon fabricating processes were investigated to determine which provided consistent bond strength and was efficient in making large quantities of coupons for the subsequent study. Next, the effect of prelube on the initial bond strength and debonding mode was investigated since the amount of prelube varies from sheet to sheet in automotive production. It was observed that even a very small change in the amount of prelube being applied on Al affected the initial bond strength. The more the prelube the weaker the bond became and the more adhesive failure occurred on the bonded Al surface. On the other hand, varying amount of the mill oil on the steel surface did not make much change to the bonding strength. Finally, various combinations of Al and steel substrates were studied to observe the effect of substrate materials on the initial bond strength and failure behavior. It revealed that the strength of joints between a relatively strong substrate and a relatively weak substrate fell below the strength of identical material joint made of the relatively strong substrate, and was closer to the strength of identical material joint made of the relatively weak substrate. For bonds having a high joint efficiency, adhesive failures were observed mostly on the surfaces of relatively weak substrates in the dissimilar material bonds due to large deformation in the weak substrate resulting in higher loading on that interface.

Effect of Tool Shape on Hole Clinching for CFRP with Steel and Aluminum Alloy Sheet

2014 ◽  
Vol 622-623 ◽  
pp. 476-483 ◽  
Author(s):  
Seung Hun Lee ◽  
Chan Joo Lee ◽  
Bong Hwan Kim ◽  
Min Su Ahn ◽  
Byung Min Kim ◽  
...  
Keyword(s):  
Dissimilar Materials ◽  
Material Design ◽  
Alloy Sheet ◽  
Automotive Body ◽  
Automotive Components ◽  
Lap Shear ◽  
Lap Shear Test ◽  
Reinforced Plastic ◽  
Tool Shape ◽  
Neck Thickness

Use of light materials such as aluminum, magnesium and carbon fiber reinforced plastic (CFRP) has been increased to achieve the light-weight car body in automotive industry. For successful multi-material design of automotive body, the joining method for dissimilar materials is required to assemble the automotive components produced by various materials. Especially, hole clinching process is effective to fasten dissimilar materials without any additional joining element. In this study, effect of tool shape on the hole clinching is investigated by FE-analysis and experiments. The parameters related to clinching tool shape are punch diameter, punch corner radius and die depth. The geometrical interlocking is evaluated by the neck-thickness and undercut. Joint strength using single lap shear test is evaluated also to verify the effectiveness of hole clinching as automotive joints.

Elastic analytical solutions and angular distributions near spot weld nugget in lap-shear specimens

2017 ◽  
Vol 233 (1) ◽  
pp. 192-203
Author(s):  
Fengxiang Xu ◽  
Fei Yan ◽  
Chao Wang ◽  
Yuqiang Li
Keyword(s):  
Analytical Solutions ◽  
Radial Distance ◽  
Spot Weld ◽  
Weld Nugget ◽  
Failure Behavior ◽  
Stress Distributions ◽  
Engineering Structures ◽  
Automotive Body ◽  
Lap Shear ◽  
Von Mises

Spot welding has been a remarkably important joint method for automotive body engineering. Based on a simplified two-dimensional analytical model in a lap-shear specimen, the elastic analytical solutions near spot weld nugget are theoretically derived to analyze stress distributions. A Cartesian coordinate system is centered at the center of the nugget, and the shear or resultant force acting on the nugget is marked as the positive x-direction. The results show that the normalized radial and hoop stresses are negative at the angle intervals between [66.25°, 113.75°] and [246.25°, 293.74°], while the normalized shear stress is negative at the angle intervals between [0°, 90°] and [180°, 270°]. It can be observed that the locations with the initial yielding failure change gradually from the normalized radial distance of 1.34 to the circumference of the spot weld nugget, and finally to the infinity as the angle increases. The normalized effective stress could approach to 1.84 as the normalized radial distance goes to infinity. In addition, the obtained analytical solutions are validated in the comparison with numerical results. The locations with peak Von Mises stresses along the circumference of the spot weld nugget have a good agreement with the analytical solutions. It indicates that the initial yielding locations would likely occur at the four special angles of the spot weld nugget. Therefore, the derived stress distributions in this study are beneficial for analyzing yielding failure behavior or evaluating damage evolution on engineering structures jointed with spot welds.

scholarly journals A Mixed Numerical-Experimental Method to Characterize Metal-Polymer Interfaces for Crash Applications

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 818
Author(s):  
Jonas Richter ◽  
Moritz Kuhtz ◽  
Andreas Hornig ◽  
Mohamed Harhash ◽  
Heinz Palkowski ◽  
...  
Keyword(s):  
Experimental Parameter ◽  
Dissimilar Materials ◽  
Calibration Method ◽  
Parameter Determination ◽  
Failure Behavior ◽  
Cohesive Elements ◽  
Interface Failure ◽  
Wide Range ◽  
Polymer Metal ◽  
Metal Polymer

Metallic (M) and polymer (P) materials as layered hybrid metal-polymer-metal (MPM) sandwiches offer a wide range of applications by combining the advantages of both material classes. The interfaces between the materials have a considerable impact on the resulting mechanical properties of the composite and its structural performance. Besides the fact that the experimental methods to determine the properties of the single constituents are well established, the characterization of interface failure behavior between dissimilar materials is very challenging. In this study, a mixed numerical–experimental approach for the determination of the mode I energy release rate is investigated. Using the example of an interface between a steel (St) and a thermoplastic polyolefin (PP/PE), the process of specimen development, experimental parameter determination, and numerical calibration is presented. A modified design of the Double Cantilever Beam (DCB) is utilized to characterize the interlaminar properties and a tailored experimental setup is presented. For this, an inverse calibration method is used by employing numerical studies using cohesive elements and the explicit solver of LS-DYNA based on the force-displacement and crack propagation results.

scholarly journals Bond Strength between Glass Fiber Fabrics and Low Water-to-Binder Ratio Mortar: Experimental Characterization

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Daniel Bohling ◽  
Andrzej Cwirzen ◽  
Karin Habermehl-Cwirzen
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Bond Strength ◽  
Glass Fiber ◽  
Penetration Depth ◽  
Pullout Strength ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
Binder Ratio ◽  
Water To Binder Ratio

Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. An experimental setup was developed and evaluated to correlate the mortar penetration depth with several key parameters. The studied parameters included fresh mortar properties, compressive and flexural strengths of mortar, the fabric/mortar bond strength, fabric pullout strength, and a single-lap shear strength. Results showed that an average penetration of mortar did not exceed 100 µm even at a higher water-to-binder ratio. The maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 µm to avoid the sieving effect, preventing effective penetration. The pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was also additionally affected by the mechanical properties of the mortar.

Joining sheets made from dissimilar materials by hole hemming

2022 ◽  
pp. 146442072110726
Author(s):  
Mohammad Mehdi Kasaei ◽  
Lucas FM da Silva
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
Dissimilar Materials ◽  
Element Analysis ◽  
Lightweight Structures ◽  
Lap Shear ◽  
Gradual Failure ◽  
Peel Tests ◽  
Dp780 Steel ◽  
Joining Process

This research work presents a new joining process based on the hemming process for attaching sheets made from dissimilar materials with very different mechanical properties. The process is termed ‘hole hemming’ and consists in producing a mechanical interlock between pre-drilled holes which can be made anywhere on the sheets. The process is carried out in a two-stage operation including flanging the hole of an outer sheet and bending the flange over the hole of an inner sheet. First, the joining stages and the required tools are designed. Then, the joining of DP780 steel and AA6061-T6 aluminium alloy sheets, which are applied to manufacture lightweight structures in the automotive industries, is investigated using finite element analysis. Results show that the hole hemming process is able to successfully join these materials without fracture. The hole-hemmed joint withstood the maximum forces of 2.5 and 0.5 kN in single-lap shear and peel tests, respectively, and failed with hole bearing mode which is known as a gradual failure mode. The results demonstrate the applicability of the hole hemming process for joining dissimilar materials.

scholarly journals Hybrid Approaches for Selective Laser Sintering by Building on Dissimilar Materials

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5285
Author(s):  
Babette Goetzendorfer ◽  
Thomas Mohr ◽  
Ralf Hellmann
Keyword(s):  
Substrate Surface ◽  
Selective Laser Sintering ◽  
Dissimilar Materials ◽  
Polyamide 6 ◽  
Laser Sintering ◽  
New Approach ◽  
Metallic Substrates ◽  
Polyamide 12 ◽  
Melting Temperatures ◽  
Hybrid Approaches

We introduced a new approach in selective laser sintering for hybrid multicomponent systems by fabricating the sintered polyamide 12 (PA12) part directly onto a similar (PA12) or dissimilar (polyamide 6 (PA6) and tool steel 1.2709) joining partner. Thus, the need for adhesive substances or joining pressure was completely circumvented, leading to the possibility of pure hybrid lightweight bi-polymer or metal–polymer systems. By taking advantage of the heating capabilities of the sinter laser regarding the substrate surface, different exposure strategies circumvented the lack of overlapping melting temperatures of dissimilar polymers. Therefore, even sintering on non-PA12 polymers was made possible. Finally, the transfer on metallic substrates—made up by selective laser melting (SLM)—was successfully performed, closing the gap between two powder-based additive processes, selective laser sintering (SLS) and SLM.

Reliability analysis of load-sharing parallel systems considering equivalent strength degradation

2020 ◽  
pp. 1748006X2096842
Author(s):  
Xinshui Yu ◽  
Tianxiang Yu ◽  
Kunling Song ◽  
Bifeng Song
Keyword(s):  
Parallel Systems ◽  
Original System ◽  
Load Sharing ◽  
Degradation Process ◽  
Strength Degradation ◽  
Parallel System ◽  
Failure Behavior ◽  
Initial Strength ◽  
Reliability Method ◽  
Equivalent Strength

In this paper, a new reliability method for load-sharing parallel systems with dependent components that share the workload equally before and after some components have failed is studied. In the working process of a load-sharing parallel system, after the failure of some components, the surviving components share the original system workload with higher components loads. The states of all the components are dependent. The failure behavior of a component impacts the strength degradation process of the remaining working components. For a load-sharing parallel system, one component works the whole system works, which means the component with the largest initial strength works, the whole system works. Firstly, we use the equivalent strength degradation theory to get the remaining strength of the component with the largest initial strength after some components fail. Then, the stress-strength interference model will be used to calculate the reliability after some components fail. Finally, the proposed method is illustrated by a numerical example and verified by the Monte Carlo simulation method.

Surface Topography Influences on the Fatigue Behavior of Composite Joints

2019 ◽  
Vol 809 ◽  
pp. 341-346 ◽  
Author(s):  
Torsten Thäsler ◽  
Jens Holtmannspötter ◽  
Hans Joachim Gudladt
Keyword(s):  
Bond Strength ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Surface Condition ◽  
Atmospheric Pressure Plasma ◽  
Fatigue Tests ◽  
Stress Concentrations ◽  
Release Agent ◽  
Structured Surfaces ◽  
Lap Shear

The surface condition of carbon fibre reinforced plastic (CFRP) substrates is decisive to obtain high bond strength and lifetime of adhesively bonded parts. Those surfaces were adjusted in terms of their microscopic topography by means of peel plies and release foils. The subsequent surface treatment via atmospheric pressure plasma jet or vacuum blasting allowed the modification of the microscopic roughness as well as the surface chemistry. Those configuration were assessed using surface analytic methods as well as quasi-static and cyclic fracture tests on single lap shear specimens. The microscopic surface roughness, if at all, only showed a small influence on the bond strength. Despite release agent residues, fracture was found within the fiber-matrix interface, which caused difficulties in evaluating the effect of surface pretreatments on the adhesion strength. Fatigue tests revealed a lifetime reduction of uneven microscopic rough surfaces, which was assigned to stress concentrations at the tip of asperities. The crack propagation was accelerated in case of release agent residues. If surfaces were free of contaminations, no differences between microscopically smooth and slightly structured surfaces were found. Overall, fatigue testing on single lap shear specimens showed an increased sensitivity with regard to the assessment of surface morphology.

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