The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kemal M Apalak - One of the best experts on this subject based on the ideXlab platform.
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stress wave propagation in a functionally graded Adhesive Layer between two identical cylinders
Journal of Adhesion, 2019Co-Authors: Mehmet Dorduncu, Kemal M Apalak, J N ReddyAbstract:ABSTRACTThis study investigates the stress wave propagation in circular aluminum cylinders bonded with a functionally graded Adhesive Layer subjected to an axial impulsive load. The Adhesive joint consists of two identical (aluminum) cylinders and a functionally graded Adhesive Layer. The volume fractions of the two constituents: aluminum and epoxy in the Adhesive Layer were functionally tailored through the Adhesive thickness by obeying a power-law. Therefore, the effective material properties at any point in the Adhesive Layer were predicted by the Mori-Tanaka homogenization scheme. The governing equations of the wave propagation in the joint were discretized by means of the finite difference method. The influence of the compositional gradient exponent on the displacement and stress distributions of the joint was examined. It was observed that changing the material composition of the Adhesive Layer had an evident effect on the displacement and stress levels, especially in the lower cylinder. On the cont...
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stress wave propagation in a through thickness functionally graded Adhesive Layer
Journal of Adhesion Science and Technology, 2019Co-Authors: Mehmet Dorduncu, Kemal M Apalak, J N ReddyAbstract:AbstractIn this study, an improved mathematical model is presented to investigate the stress wave propagation in two circular cylinders bonded with a functionally graded Adhesive Layer. In the prop...
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elastic flexural behaviour of an Adhesively bonded single lap joint with functionally graded adherends
Materials & Design, 2007Co-Authors: Kemal M Apalak, Recep GunesAbstract:Abstract This study investigates three-dimensional elastic flexural behaviour of an Adhesively bonded single lap joint with adherends composed of a functionally gradient Layer between a pure ceramic (Al2O3) Layer and a pure metal (Ni) Layer. The in-plane normal stress and shear stresses were critical in the adherends and Adhesive Layer. The left free edge of the upper adherend–Adhesive interface, the right free edge of the lower adherend–Adhesive interface and the corresponding zones in the upper and lower adherends experience stress concentrations whereas the middle overlap region has a uniform low stress distribution. The normal stress varies linearly through the adherend thickness and then becomes peak in the ceramic Layer and in the metal Layer. In the Adhesive Layer, the normal stress is peak at the left free edge of the upper adherend–Adhesive interface and at the right free edge of the lower adherend–Adhesive interface and then decreases uniformly across the Adhesive Layer towards the other adherend–Adhesive interface. The functionally gradient region composed of Layers with the mechanical properties calculated based on the power law. Accordingly, increasing the Layer number had a minor effect on the through-the-thickness profiles and magnitudes of the critical stresses in both the adherends and the Adhesive Layer. In addition, enriching the material composition of the functionally gradient region with the ceramic phase does not affect the through-the-thickness profiles of critical normal and shear stresses of both adherends and Adhesive whereas their magnitudes in the ceramic-rich Layer of both adherends and along the adherend–Adhesive interfaces increase considerably. On the contrary, the Layer number and compositional gradient component affect evidently the through-the-thickness profiles and magnitudes of the critical normal and shear stresses in the adherends and Adhesive Layer of the functionally graded Adhesively bonded joints subjected to thermal loads.
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investigation of elastic stresses in an Adhesively bonded single lap joint with functionally graded adherends in tension
Composite Structures, 2005Co-Authors: Kemal M Apalak, Recep GunesAbstract:Abstract In this study three-dimensional elastic stress state of an Adhesively bonded single lap joint with functionally graded adherends in tension was investigated. The adherends compose of a functionally gradient Layer between a pure ceramic (Al 2 O 3 ) Layer and a pure metal (Ni) Layer. Stress concentrations are observed along the free edges of the Adhesive Layer and through the corresponding zones in the upper and lower adherends. The Adhesive Layer experiences stress concentrations along the left and right free edges in the horizontal plane, and the normal stresses and the shear stress σ xy are critical. Whereas the middle overlap region has a uniform low stress distribution the zones in the upper adherend corresponding to the left free edge of the Adhesive Layer and the zones in the lower adherend corresponding to the right free edge of the Adhesive Layer are subjected to higher stresses. The normal stress σ xx among the normal stresses and the shear stress σ xy among the shear stresses are dominant in both upper and lower adherends. The normal stress σ xx changes uniformly from compression in the ceramic Layer to tension in the metal Layer through the upper plate-thickness and from tension in the ceramic Layer to compression in the metal Layer through the lower plate-thickness. In the Adhesive Layer, the normal stress σ yy becomes peak at the left free edge of the upper adherend–Adhesive interface and at the right free edge of the lower adherend–Adhesive interface and then decreases uniformly across the Adhesive Layer towards the other adherend–Adhesive interface. The functionally gradient region across the adherend thickness was modelled using the Layers with the mechanical properties calculated based on the power law. However, a Layer number larger than 20 has a minor effect on the through-thickness profiles and magnitudes of von Mises and normal stresses in both the adherends and the Adhesive. In addition, increasing the ceramic phase in the material composition (compositional gradient exponent n ) of the functionally gradient region does not affect the through-thickness profiles of von Mises and normal stresses in the adherends and Adhesive whereas their magnitudes in the ceramic rich Layer of both adherends and along the adherend–Adhesive interfaces increase considerably. On the contrary, the Layer number and compositional gradient exponent have an evident effect on the through-thickness profiles and magnitudes of the critical stress components in the adherends and Adhesive Layer of the functionally graded Adhesively bonded joints.
Recep Gunes - One of the best experts on this subject based on the ideXlab platform.
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elastic flexural behaviour of an Adhesively bonded single lap joint with functionally graded adherends
Materials & Design, 2007Co-Authors: Kemal M Apalak, Recep GunesAbstract:Abstract This study investigates three-dimensional elastic flexural behaviour of an Adhesively bonded single lap joint with adherends composed of a functionally gradient Layer between a pure ceramic (Al2O3) Layer and a pure metal (Ni) Layer. The in-plane normal stress and shear stresses were critical in the adherends and Adhesive Layer. The left free edge of the upper adherend–Adhesive interface, the right free edge of the lower adherend–Adhesive interface and the corresponding zones in the upper and lower adherends experience stress concentrations whereas the middle overlap region has a uniform low stress distribution. The normal stress varies linearly through the adherend thickness and then becomes peak in the ceramic Layer and in the metal Layer. In the Adhesive Layer, the normal stress is peak at the left free edge of the upper adherend–Adhesive interface and at the right free edge of the lower adherend–Adhesive interface and then decreases uniformly across the Adhesive Layer towards the other adherend–Adhesive interface. The functionally gradient region composed of Layers with the mechanical properties calculated based on the power law. Accordingly, increasing the Layer number had a minor effect on the through-the-thickness profiles and magnitudes of the critical stresses in both the adherends and the Adhesive Layer. In addition, enriching the material composition of the functionally gradient region with the ceramic phase does not affect the through-the-thickness profiles of critical normal and shear stresses of both adherends and Adhesive whereas their magnitudes in the ceramic-rich Layer of both adherends and along the adherend–Adhesive interfaces increase considerably. On the contrary, the Layer number and compositional gradient component affect evidently the through-the-thickness profiles and magnitudes of the critical normal and shear stresses in the adherends and Adhesive Layer of the functionally graded Adhesively bonded joints subjected to thermal loads.
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investigation of elastic stresses in an Adhesively bonded single lap joint with functionally graded adherends in tension
Composite Structures, 2005Co-Authors: Kemal M Apalak, Recep GunesAbstract:Abstract In this study three-dimensional elastic stress state of an Adhesively bonded single lap joint with functionally graded adherends in tension was investigated. The adherends compose of a functionally gradient Layer between a pure ceramic (Al 2 O 3 ) Layer and a pure metal (Ni) Layer. Stress concentrations are observed along the free edges of the Adhesive Layer and through the corresponding zones in the upper and lower adherends. The Adhesive Layer experiences stress concentrations along the left and right free edges in the horizontal plane, and the normal stresses and the shear stress σ xy are critical. Whereas the middle overlap region has a uniform low stress distribution the zones in the upper adherend corresponding to the left free edge of the Adhesive Layer and the zones in the lower adherend corresponding to the right free edge of the Adhesive Layer are subjected to higher stresses. The normal stress σ xx among the normal stresses and the shear stress σ xy among the shear stresses are dominant in both upper and lower adherends. The normal stress σ xx changes uniformly from compression in the ceramic Layer to tension in the metal Layer through the upper plate-thickness and from tension in the ceramic Layer to compression in the metal Layer through the lower plate-thickness. In the Adhesive Layer, the normal stress σ yy becomes peak at the left free edge of the upper adherend–Adhesive interface and at the right free edge of the lower adherend–Adhesive interface and then decreases uniformly across the Adhesive Layer towards the other adherend–Adhesive interface. The functionally gradient region across the adherend thickness was modelled using the Layers with the mechanical properties calculated based on the power law. However, a Layer number larger than 20 has a minor effect on the through-thickness profiles and magnitudes of von Mises and normal stresses in both the adherends and the Adhesive. In addition, increasing the ceramic phase in the material composition (compositional gradient exponent n ) of the functionally gradient region does not affect the through-thickness profiles of von Mises and normal stresses in the adherends and Adhesive whereas their magnitudes in the ceramic rich Layer of both adherends and along the adherend–Adhesive interfaces increase considerably. On the contrary, the Layer number and compositional gradient exponent have an evident effect on the through-thickness profiles and magnitudes of the critical stress components in the adherends and Adhesive Layer of the functionally graded Adhesively bonded joints.
Haiying Huang - One of the best experts on this subject based on the ideXlab platform.
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effects of Adhesive thickness on the lamb wave pitch catch signal using bonded piezoelectric wafer transducers
Smart Materials and Structures, 2016Co-Authors: Mazharul Islam, Haiying HuangAbstract:This paper investigates the effects of Adhesive Layer on Lamb wave ultrasound pitch-catch signals that are excited and sensed by piezoelectric wafer transducers bonded on a slender structure. Analytical models were established to simulate the longitudinal and flexural vibrations of the structures separately and parametric studies of the bonding Layer properties, i.e. the shear transfer parameter, Adhesive thickness, and shear modulus, were performed. The parametric studies indicate that there exists an optimal Adhesive Layer thickness that generates maximum ultrasound pitch-catch signal for both wave modes. This prediction was subsequently validated by measurements. In addition, an improved match between the measured and simulated pitch-catch signals was achieved by adjusting the Adhesive Layer parameters.
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understanding the effects of Adhesive Layer on the electromechanical impedance emi of bonded piezoelectric wafer transducer
Smart Materials and Structures, 2014Co-Authors: Mazharul Islam, Haiying HuangAbstract:This paper investigates the effects of the Adhesive Layer on the admittance of bonded piezoelectric wafer active sensors (PWASs) through mode identification, parametric studies, and experimental verification. Based on the time-frequency analysis of the broadband ultrasound pitch-catch signal, we discovered that the resonances of the PWAS actuator bonded on a thin slender structure are associated with the longitudinal and flexural modes of the structure. Subsequently, a physics-based shear transfer parameter was introduced to establish a multi-mode analytical model. Parametric studies were carried out to study the effects of the Adhesive Layer on the frequencies and amplitudes of the PWAS resonances. Based on the insights gained from the parametric studies, the simulated resonant frequencies of the PWAS were matched with the experimental measurements by adjusting the unknown Adhesive Layer parameters.
Tobias Andersson - One of the best experts on this subject based on the ideXlab platform.
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modeling and parameter calibration of an Adhesive Layer at the meso level
Mechanics of Materials, 2008Co-Authors: Kent Salomonsson, Tobias AnderssonAbstract:A mesomechanical finite element model of a thin Adhesive Layer is developed. The model is calibrated to previously performed experiments. In these, the Adhesive Layer is loaded in monotonically increasing peel or shear. An in situ SEM study is also performed and used to guide the modeling and calibration. The purpose of the mesomechanical finite element model is to facilitate the development of constitutive laws for Adhesive Layers. The modeling is based on Xu and Needleman’s method where all continuum finite elements are surrounded by interface elements that allow for the development of micro cracks. Thus, this enables the modeling of the entire process of degradation and fracture of the Adhesive Layer. A genetic algorithm is developed for the calibration. The simulations show good agreement with the experiments.
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on the effective constitutive properties of a thin Adhesive Layer loaded in peel
International Journal of Fracture, 2006Co-Authors: Tobias Andersson, Anders BielAbstract:An experimental method to determine the complete stress-elongation relation for a structural Adhesive loaded in peel is presented. Experiments are performed on the double cantilever beam specimen, which facilitates a more stable experimental set-up as compared with conventional methods like the butt-joint test. The method is based on the concept of equilibrium of the energetic forces acting on the specimen. Two sources of energetic forces are identified: the start of the Adhesive Layer and the positions of the two acting loads. By use of the concept of equilibrium of energetic forces, it is possible to measure the energy release rate of the Adhesive Layer instantaneously during an experiment. The complete stress-elongation relation is found to be the derivative of the energy release rate with respect to the elongation of the Adhesive Layer at its start. By this procedure, an effective property of the Adhesive Layer is measured. That is, the fields are assumed to be constant through the thickness of the Layer and only vary along the Layer. To investigate the validity of this approach, experiments are performed on five different groups of specimens with different dimensions. This leads to large variations in the length of the damage zone at the start of the Adhesive Layer. Four of the experimental groups are used to determine the stress-elongation relation. This is found to be independent of the geometry. For the remaining experimental group, the adherends deform plastically and simulations are performed with the stress-elongation relation determined from the four elastic groups. It is found that the relation cannot be used to accurately predict the behaviour of the experiments where the adherends deform plastically. This indicates that the stress-elongation relation has limited applicability.
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the stress elongation relation for an Adhesive Layer loaded in peel using equilibrium of energetic forces
International Journal of Solids and Structures, 2004Co-Authors: Tobias Andersson, Ulf StighAbstract:An experimental method to determine the stress–elongation relation for a thin Adhesive Layer loaded in peel is presented. The method is based on equilibrium of the energetic forces acting on a DCB- ...
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an experimental method to determine the complete stress elongation relation for a structural Adhesive Layer loaded in peel
European Structural Integrity Society, 2000Co-Authors: Ulf Stigh, Tobias AnderssonAbstract:Abstract An experimental method to determine the complete stress-elongation relation of a thin Adhesive Layer loaded in peel is presented. Experiments are performed on a DCB-specimen. Balance of the energetic forces is used to calculate the stress-elongation relation from experimental data. The calculation requires differentiation of the data, which puts great demands on the quality of data acquisition. The experiment is first simulated and random errors are added to simulate deficiencies in the experimental setup. These data are used to determine the required accuracy. Two sets of experimental results are presented and it is shown that a simple stress-elongation relation fits the data accurately. Elastic stiffness and fracture energy agrees favourably with independent measurements. An unexpected result is the low maximum strength of the Adhesive. Independently performed uniaxil tension tests give the yield strength 30 MPa. Taking into consideration the constraint of the Adhesive Layer and using the von Mises yield criteria gives the expected yield strength 90 MPa. However, our tests give a maximum strength of about 20 MPa. This indicates that damage is a more important factor than plasticity for the peel properties of the Adhesive Layer.
C L Davidson - One of the best experts on this subject based on the ideXlab platform.
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effect of Adhesive Layer properties on stress distribution in composite restorations a 3d finite element analysis
Dental Materials, 2002Co-Authors: Pietro Ausiello, Antonio Apicella, C L DavidsonAbstract:Abstract Objectives: Teeth, Adhesively restored with resin-based materials, were modeled by 3D-finite elements analysis that showed a premature failure during polymerization shrinkage and occlusal loading. Methods: Simulation of Class II MOD composite restorations with a resin bonding system revealed a complex biomechanical behavior arising from the simultaneous effects of polymerization shrinkage, composite stiffness and Adhesive interface strain. Due to a polymerization contraction, shrinkage stress increases with the rigidity of the composites utilised in the restoration, while the cusp movements under occlusal loading are inversely proportional to the rigidity of the composites. The Adhesive Layer's strain also plays a relevant role in the attenuation of the polymerization and occlusal loading stresses. Results: The choice of an appropriately compliant Adhesive Layer, able to partially absorb the composite deformation, limits the intensity of the stress transmitted to the remaining natural tooth tissues. For Adhesives and composites of different rigidities, FEM analysis allows the determination of the optimal Adhesive Layer thickness leading to maximum stress release while preserving the interface integrity. Application of a thin Layer of a more flexible Adhesive (lower elastic modulus) leads to the same stress relief as thick Layers of less flexible Adhesive (higher elastic modulus).