scholarly journals Evaluation of Single-Lap and Block Shear Test Methods in Adhesively Bonded Composite Joints

2021 ◽  
Vol 5 (1) ◽  
pp. 27
Author(s):  
Alec Redmann ◽  
Vinay Damodaran ◽  
Felix Tischer ◽  
Pavana Prabhakar ◽  
Tim A. Osswald
Keyword(s):  
Composite Structures ◽  
Joint Strength ◽  
Adhesive Bonding ◽  
Failure Modes ◽  
Shear Loading ◽  
Analytical Models ◽  
Normal Stresses ◽  
Block Shear ◽  
Lap Shear ◽  
Shear Joint

Adhesive bonding is increasingly being used for composite structures, especially in aerospace and automotive industries. One common joint configuration used to test adhesive strength is the single-lap shear joint, which has been widely studied and shown to produce significant normal (peeling) stresses. When bonding composite structures, the normal stresses are capable of causing delamination before the adhesive bond fails, providing inconclusive engineering data regarding the bonding strength. An alternative test is the block shear joint, which uses a shorter sample geometry and a compressive-shear loading to reduce normal stresses. Analytical models proposed by Goland and Reissner and Hart-Smith are used to compare the edge-bending moment for the two joint configurations. The stress distributions along the bondline are also compared using finite element analysis. Experimental tests are conducted to evaluate these analyses and the failure modes of each configuration are recorded. Block shear samples demonstrate a joint strength over 100% higher than single-lap shear specimen bonded with the same adhesive material. The lower joint strength measured in single-lap shear is found to be potentially misleading due to delamination of the composite adherend.

Static and Impact Behavior of Self-Pierced Rivet Connections in Aluminum

2001 ◽  
Author(s):  
Chelliah Madasamy ◽  
Omar Faruque ◽  
Tau Tyan ◽  
Robert Thomas
Keyword(s):  
Strain Rate ◽  
Design Process ◽  
Failure Modes ◽  
Shear Loading ◽  
Peak Force ◽  
Impact Behavior ◽  
Impact Performance ◽  
Lap Shear ◽  
Shear Modes ◽  
Importance Assessment

Abstract Self-pierced riveted (SPR) connections in aluminum coupons were tested to evaluate their static and impact performance for automotive vehicle applications. The variables studied included: top gage, bottom gage, rivet size, adhesive, pre-strain, rivet location, strain-rate, and temperature. The SPR connections were tested for coach peel, u-tension, and lap shear modes. A variable importance assessment as well as the estimated effect of the variables on peak force and energy absorption was determined. The failure modes observed during testing were consistent. From this study, it was found that the top gage, bottom gage, and temperature were very sensitive for coach peel, u-tension, and lap shear. Additionally, adhesive was found to be important for shear loading, strain-rate increased the peak force when adhesive was present and, rivet size had a significant effect on both u-tension and coach peel modes. The effect of pre-strain and rivet location was minimal, and therefore their effect in the design process can be considered minimal.

scholarly journals Failure Modes and Resistance of Perforated Steel Rib Shear Connectors under Uplift Forces

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Xiaoqing Xu ◽  
Yuqing Liu
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Analytical Models ◽  
Shear Connectors ◽  
Steel Bar ◽  
Concrete Damage ◽  
Uplift Resistance ◽  
Transverse Steel ◽  
Uplift Forces

In recent years, there is a rapid increase in the application of perforated steel rib shear connectors in steel and concrete composite structures. The connectors must not only ensure shear transfer but also sufficient uplift resistance. The shear behavior of connectors has been extensively investigated. However, studies on uplift resistance are lacking so far. Therefore, three push-out test specimens were tested to investigate the shear and tension behavior of perforated L-shaped and plain steel rib shear connectors. The failure modes of connectors were analyzed, and analytical models for the determination of uplift resistance were derived based on test results. The results showed that the ductility of perforated steel rib shear connectors under uplift force was smaller than that under shear force, and more severe concrete damage surrounding the rib and larger bending deformation of transverse steel bar was observed. The rib flange of L-shaped perforated rib has a significant contribution to the uplift resistance. It was suggested to increase the rib height of L-shaped rib to avoid the horizontal crack at the height of the rib flange. The validity of the proposed analytical models was confirmed by comparing the failure modes and capacities of specimens.

Combined Puncture and Cutting of Soft-Coated Fabrics by a Pointed Blade: Energy, Force and Stress Failure Criteria

2019 ◽  
pp. 152808371987388
Author(s):  
Ennouri Triki ◽  
Chantal Gauvin
Keyword(s):  
Total Energy ◽  
Cutting Force ◽  
Failure Modes ◽  
Stress Component ◽  
Shear Loading ◽  
Critical Force ◽  
Analytical Models ◽  
Protective Gloves ◽  
Coated Fabrics ◽  
Soft Elastomer

Soft elastomer-coated fabrics are widely used in engineering and protective applications. Puncture cutting by sharp-tipped objects is one of the most common failure modes of protective gloves made of coated fabrics. In order to investigate the puncture-cutting process of soft elastomer-coated fabrics, we studied the mechanisms and mechanics of pointed-blade insertion into specimens cut out from four protective gloves. Experimental and analytical analyses showed that total energy and critical puncture-cutting force calculated analytically are both able to predict the puncture-cutting resistance of soft elastomer-coated fabrics measured experimentally. Total energy is obtained from the relationship between the puncture-cutting work and the created fracture area, while critical force is calculated by two analytical models developed for soft elastomeric membranes. The components of the critical puncture-cutting force are predicted analytically and then used to calculate the compressive and shear loading stress components based on the contact surface between the pointed blade tip and material. Since there is a linear relationship between the compressive stress component and shear stress component, a modified linear strength criterion is proposed for puncture cutting of soft elastomer-coated fabrics by a pointed blade. Our stress-based criterion connects the 45° tensile strength (in the 45° direction) and biaxial strengths (in the course direction, 0°, and wale direction, 90°) to both compressive and shear loading stresses. The analytical and experimental results are consistent. This investigation can be used as a guideline to evaluate the puncture cutting of soft elastomer-coated fabrics using an energy-based criterion, critical force-based criterion, or stress-based criterion.

Numerical modelling of multi-material graded joints under shear loading

2020 ◽  
Vol 234 (5) ◽  
pp. 436-445
Author(s):  
Mateus Q dos Reis ◽  
Ricardo JC Carbas ◽  
Eduardo AS Marques ◽  
Lucas FM da Silva
Keyword(s):  
Numerical Model ◽  
Joint Strength ◽  
Adhesive Bonding ◽  
Numerical Models ◽  
Shear Loading ◽  
Lap Joints ◽  
Functionally Graded ◽  
Stress Concentrations ◽  
Adhesive Properties ◽  
Element Analysis

Due to environmental concerns, modern transportation solutions demand drastic reductions of fuel consumption and emissions, which can only be achieved with advanced structures using high-performance lightweight materials. For joining these dissimilar materials, adhesive bonding appears as an optimal solution, since mechanical fastening adds weight to the structure, and welding technology is not easily applicable to reinforced plastics and composites. However, one of the major drawbacks associated with bonded joints is the presence of stress concentrations at the overlap ends, especially in single lap joints. In order to reduce these stress concentrations, several techniques have been developed. One of these is the functionally graded adhesive, in which the adhesive properties gradually vary along the overlap length, leading to a more uniform stresses distribution and improving the joint strength. However, the manufacture of an adhesive layer with properties which gradually vary is complex in practice and so is the creation of numerical models that represent these configurations. In the present work, a numerical model for different-graded distribution of adhesive properties along the overlap was developed, using programmed step functions on finite element analysis background in order to discretize and simplify the continuous properties distribution gradient. Cohesive zone modelling was introduced in the numerical model, enabling it to effectively predict graded joint strength. The model was validated with experimental results of functionally graded joints available in the literature. The numerical model developed presents itself as a powerful tool to predict joint strength for functionally graded joints, without imposing large computational demands.

Performance of double skin-profiled composite shear walls — experiments and design equations

2004 ◽  
Vol 31 (2) ◽  
pp. 204-217 ◽  
Author(s):  
K M. Anwar Hossain ◽  
H D Wright
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Failure Modes ◽  
Shear Walls ◽  
Shear Stiffness ◽  
Response Strength ◽  
Shear Loading ◽  
Analytical Models ◽  
Small Scale ◽  
Composite Wall

The novel form of composite walling system consists of two skins of profiled steel sheeting with an infill of concrete. The knowledge of the behaviour of such walling under shear loading is important to use this system as shear elements in a steel framed building. Currently design provisions for this novel form of framed shear walling do not exist. This paper presents the results of tests on one-sixth scale models of the composite wall and its components, manufactured from very thin sheeting and microconcrete. The heavily instrumented small-scale tests provided information on the load–deflection response, strength, stiffness, strain condition, sheet–concrete interaction, and failure modes. Analytical models for the shear strength and stiffness of the wall are derived. The adequacy of design equations is validated through experimental results and finite element modelling.Key words: composite wall, design equation, profiled sheeting, shear strength, shear stiffness, strain, buckling, finite element, interface, microconcrete.

Spot Friction Weld Strength Improvement Through In-Process Metal Matrix Formation

2008 ◽  
Author(s):  
Senthil Arul ◽  
Grant H. Kruger ◽  
Scott F. Miller ◽  
Tsung-Yu Pan ◽  
Albert J. Shih
Keyword(s):  
Metal Matrix ◽  
Joint Strength ◽  
Steel Powder ◽  
Weld Strength ◽  
Depth Of Penetration ◽  
Maximum Increase ◽  
Lap Shear ◽  
Shear Joint ◽  
Lower Depth ◽  
Friction Weld

The effects of metal matrix composite (MMC) on the joint strength of Spot Friction Welded (SFW) specimens made of Al 1100 and Al 6111 alloys are studied. The MMC-SFW joints were created by sandwiching metal reinforcing powder (<75μm mesh) between the upper (1.3mm thick) and lower (1.5mm thick) Al coupons, at the center of the SFW joint. To maximize the heat input into the specimen, a Zirconium (ZrO2) ceramic anvil was used. Depth of penetration of the tool played an important role in determining the distribution of the reinforcing material within the MMC during plastic mixing in the SFW joint, and hence its influence on the joint strength. At a lower depth of penetration, 2.1 mm, the results showed that the MMC-SFW reinforced with Ancorsteel 1000, copper or Al12Si powders did not increase the joint strength since they did not spread uniformly in the stir zone. However, at a higher depth of penetration, 2.5 mm, the MMC-SFW joint reinforced with Ancorsteel 1000, copper, or Al12Si did increase the joint strength compared to that of the base SFW specimens. Using steel powder as the reinforcement material, the MMC showed the maximum increase in the lap shear joint strength. For example, at 2.5 mm depth of penetration, the SFW joint strength increased by 19% and 24% compared to that of the base SFW specimen made of Al 1100 and Al 6111 alloys respectively.

Fastening composite structures using braided thermoplastic composite rivets

2019 ◽  
Vol 54 (6) ◽  
pp. 801-812 ◽  
Author(s):  
Vincent Fortier ◽  
Jean-E Brunel ◽  
Louis L Lebel
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Joint Strength ◽  
Breaking Load ◽  
Bolted Joints ◽  
Thermoplastic Composite ◽  
Lap Shear ◽  
Riveted Joints ◽  
Manufacturing Performance ◽  
Unbalanced Load

Aerospace composite material components are currently joined using heavy titanium bolts. This joining method is not ideal when considering its weight, thermal expansion, electrical conductivity, and risk of unbalanced load distribution. We propose here an innovative fastening technology using thermoplastic composite rivets. A rivet blank is heated above its melting temperature using Joule heating and is formed directly in the composite laminates by an automated process. Carbon fiber and polyamide blanks were used with two fiber architecture: 2D braid and unidirectional. The braided architecture showed superior manufacturing performance and repeatability. Joints were riveted in less than 40 s per rivet. The temperature measured in the riveted composite laminate in the vicinity of formed rivet reached only 136℃ during riveting. Double fastener lap shear testing showed breaking load of 6146 N per fastener. This joint strength is higher than comparable aluminum-riveted joints, and the specific joint strength is higher than titanium-bolted joints. With these advantages, the technology could be developed and used in the next generations of lighter, cleaner, and safer aircraft.

scholarly journals An investigation of the stitching effect on single lap shear joints in laminated composites

2019 ◽  
Vol 26 (1) ◽  
pp. 509-516
Author(s):  
Wang Peiyan ◽  
Geng Xiaoliang ◽  
Zhao Chen ◽  
Zhang Rongshuo
Keyword(s):  
Elevated Temperature ◽  
Bond Strength ◽  
Composite Laminates ◽  
Composite Structures ◽  
Failure Modes ◽  
Epoxy Adhesive ◽  
Lap Joints ◽  
Single Lap Joints ◽  
Working Environments ◽  
Lap Shear

Abstract This paper aimed to investigate the stitching effect on the bond strength of single lap shear joints in carbon/epoxy composite laminates using experimental and simulation methods. Stitched and unstitched single lap shear joints were bonded using the EC-3448 epoxy adhesive and tested under different working environments, including room temperature/dry (RTD), elevated temperature/wet (ETW) and cold temperature/dry (CTD). The results showed that stitching improved the bond strength of the stitched single lap joints, with approximately 60% higher strength for stitched compared to unstitched lap joints under RTD and CTD environments and 10% higher strength under an ETW environment. The increase was smaller under ETW conditions because the adhesive recured under elevated temperature. Embedded interactions connected the lapping plates and the stitch line, and the maximum stress failure criterion was adopted for the stitch line. As the predicted failure modes are consistent with the experimental results, the progressive damage mode can be applied to simulate stitched composite structures.

Effects of thermal aging on long-term reliability and failure modes of nano-silver sintered lap-shear joint

2020 ◽  
Vol 97 ◽  
pp. 102488 ◽  
Author(s):  
Yansong Tan ◽  
Xin Li ◽  
Gang Chen ◽  
Qitong Gao ◽  
Guo-Quan Lu ◽  
...  
Keyword(s):  
Thermal Aging ◽  
Failure Modes ◽  
Nano Silver ◽  
Lap Shear ◽  
Shear Joint
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