Tensile Behaviour of a Structural Adhesive at High Temperatures by the eXtended Finite Element Method (original) (raw)
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Systematic Evaluation of Bonding Strengths and Fracture Toughnesses of Adhesive Joints
Journal of Adhesion, 2011
A systematic experimental investigation to determine the shear, tensile, and fracture properties of adhesive joints with bonded same-materials (polymer-polymer) and bi-materials (metal-polymer) is reported. Full-field optical techniques including photoelasticity and coherent gradient sensing (CGS) are employed to record the stress development and failure in these adhesive joints. Five types of strong and weak adhesives are used in conjunction with five different types of materials [aluminum, steel, polymethylmethacrylate (PMMA), polycarbonate, and Homalite®-100] to produce a variety of bonded material systems. Weld-on®-10 and a polyester bonding consistently show higher tensile and shear bonding strengths. Bi-material systems in shear and fracture report lower properties than the same-material systems due to a higher property mismatch in the former. The resulting complete experimental data are expected to be immensely helpful to computational mechanists in simulating failure mechanics of adhesive joints.
Fracture toughness and shear behavior of composite bonded joints based on a novel aerospace adhesive
Composites Part B: Engineering, 2012
In this paper, the mechanical performance of the newly developed LMB aerospace structural adhesive has been characterized experimentally. To this end, a comparison has been performed with the Epibond 1590 A/B adhesive on the basis of the effects of thermal aging, wet aging and adhesive thickness on the fracture toughness and shear behavior (static and fatigue) of bonded joints between CFRP laminates. Mode-I and -II fracture toughness was measured through tensile and 3-point bending tests on doublecantilever beam specimen, respectively, while the shear behavior of the joints was assessed through static and fatigue double-lap shear tests. A fractographic analysis of the fracture surfaces was performed in order to detect the failure mode of the bonded joint. The experimental results show a higher fracture toughness and improved fatigue behavior for the LMB adhesive.
Materials Today: Proceedings, 2020
The efficient and economic structures are high in demand in various firms due to the requirement of lightweight, a feasible joining of similar/dissimilar materials, safety and high durability. Adhesively bonded multi-material joints are coming into use in various structural applications due to the potential utilization of the merits of individual constituents. This research work provides the importance of adhesively bonded joints with different material combinations, which in turn were investigated experimentally. The present paper involves joining of tin as metal and glass fiber reinforced polymer (GFRP) as composite resulting in combinations as GFRP-GFRP, GFRP-Metal, and Metal-Metal Single lap joints (SLJs). The lap joint efficiency test results revealed that the highest lap shear strength was exhibited by GFRP-GFRP SLJ, amounting to a value of 6.84 ± 0.08 MPa. A decrement of 10.98% and 33.17% was recorded for Metal to GFRP and Metal-Metal SLJs, respectively. Similar trend was observed in maximum load underwent by different SLJs, where in GFRP-GFRP SLJ exhibited the highest load bearing capacity of 4280 ± 25 N. The Metal-Metal SLJs indicated the highest shear stiffness value of 4.48 MPa/mm, whereas the GFRP-Metal yielded into the highest toughness value of 21.56 ± 0.44 MPa*mm. Further, the fracture surfaces of SLJs revealed that there was a combination of cohesive and adhesive failures.
Principles and practices of adhesive bonded structural joints and repairs
International Journal of Adhesion and Adhesives, 1999
Adhesive bonding has been used for a number of decades for construction of aircraft components. Light weight sandwich construction and structural bonded joints form a major proportion of modern aircraft. Bonded patches are also used for repair of sandwich panels, cracks in metallic structure or reinforcement of de"cient structures. The in-service durability of bonded structures and repairs has varied dramatically, with some structures and repairs providing life-of-type service and others failing in a very short time, leading to a poor acceptance by aircraft operators of adhesive bonded structures and repairs. A corresponding reluctance has occurred amongst manufacturers and repair authorities to accept the superior performance of adhesive bonding which has been demonstrated in laboratory and "eld trials over a number of decades. The variability of bonded joints can occasionally be traced to de"cient bonded joint design, but usually the de"ciency lies in a lack of understanding of the adhesive bonding processes. If some basic principles are applied (and preferably embodied in some form of design and processing standard for airworthiness certi"cation) reliable adhesive bonded structures and repairs would achieve a signi"cantly superior performance over conventional mechanically fastened systems. This paper details basic principles required for the production of strong, durable adhesive bonds.
Mechanical Strength of Adhesively Bonded Metals
Adhesives - Science, Technology, Recent Advances, and Applications [Working Title]
Adhesive joints are nowadays widely used in fields ranging from packaging to aeronautics. Nevertheless, the absence of accurate failure criteria remains an important obstacle that often prevents the use of adhesive joints in structural applications. The main objective of this work is to be an introduction to the subject, and it was for this to evaluate the factors that most influence the strength of overlap adhesive joints.
Adhesively Bonded Carbon/Titanium Joints Under In-plane and Bending Loads
T he goal of this research is to optimize the design of single-lap joints made by joining composite material to metals. The single-lap joint under both out-of-plane load and tensile load was examined. It is observed that designing a joint for one kind of load is not always satisfactory because for other load cases, different stresses would govern the design. Local stress peaks were investigated in order to find ways to decrease these peaks. An approach for optimizing the joint was chosen so the stress peaks at each end could be minimized (peel, axial and shear stress). By tapering the titanium adherend inside and outside, the stress distribution in the adhesive can be significantly changed at the tapered end and all three important stresses that governed the design (peel, axial and shear stress) are decreased for a joint under tension and out-of-plane load. For dissimilar adherends, the numerically largest stresses always occur in the adhesive at the edge of the overlap adjacent to the adherend with the lower value of flexural stiffness and the relative difference in these peaks is a function of the relative flexural stiffness of two adherends. Using an outer bead of adhesive decreases the stress peak at composite edge. Thus, two methods are used to reduce adhesive stresses: tapering and addition of adhesive beads. Having completed a finite element stress analysis, the results are used to predict the strength of a given joint. A strain energy based on failure criteria was evaluated, which addressed the problem of stress singularities in the finite element method. Three point bending tests were performed using different bonding configurations to verify the strength of the adhesive joint and to evaluate the failure criterion. Optimization of the parameters of the joint geometry was achieved from the results of this study.
Strength assessment of adhesive-bonded joints
Computational Materials Science, 2008
This paper deals with non-linear analyses of adhesively bonded joints under tensile lap shear loading. 3D FEM models are taken into account. The effect of the number of elements through the adhesive layer thickness is considered. Tensile true stress-true strain curves are used as models of the adherend and adhesive materials. The single lap joints are tested to validated the numerical analyses.
Comparative evaluation of bonded, welded and weld-bonded structural joints
A variety of methods to join structural components is available nowadays. Joining with high-strength adhesives is presently widespread for advanced structures such as aerospace or aeronautical, on account of a few distinctive advantages over traditional methods (elimination of drilling operations and distribution of loads over a larger area than mechanical joints). Nonetheless, stress concentrations emerge at the overlap ends because of the adherends straining and load asymmetry, which can result on premature fractures. Structural joints can equally be severely affected by the surface treatment of the bonding surfaces, extreme environmental conditions and ageing. Weld-bonded joints (combination of adhesive bonding with spot-welding) can surpass these disadvantages, adding a superior static strength and stiffness, and higher peeling and fatigue strength. This work presents and experimental and numerical study comparing hybrid spot-welded/bonded single-lap joints with purely spot-weld...