Finite Element Stress Response Analysis of Stepped-Lap Adhesive Joints of Similar Adherends Under Impact Tensile Loadings

Author(s):  
Toshiyuki Sawa ◽  
Takahiro Oomori ◽  
Kohei Ichikawa ◽  
Shoichi Kido

The stress variations and stress distributions in stepped-lap adhesive joints of similar adherends under impact tensile loadings were analyzed in elastic range using three-dimensional finite element method (DYNA3D). The impact loadings were applied to the lower adherend by dropping a weight. The stress distributions in stepped-lap adhesive joints of similar adherends under static tensile loadings were also analyzed using FEM (MARC). The effects of Young’s modulus of the adherends, the adhesive thickness, and a number of steps in the adherends on the stress variations and the stress distributions at the interfaces between the adherends and the adhesive were examined under both impact and static loadings. As the results, it was found that (1) the maximum value of the maximum principal stress σ1 occured at the outside edge of the butted interface between the adhesive and the lower adherend to which impact loadings were applied; (2) The maximum value of stress σ1 increased as Young’s modulus of the adherends increased; (3) The maximum value of stress σ1 increased as the adhesive thickness decreased, and it increased at the butted parts of joints as the adhesive thickness decreased. The maximum value of stress σ1 increased at the lapped parts of joints as the adhesive thickness increased; (4) The maximum value of stress σ1 increased as the numbers of steps in the adherends increased. The characteristic of the joints under static loadings were also clarified. In addition, the experiments to measure the strain response of joints subjected to impact tensile loadings were carried out using strain gauges. A fairly good agreement was found between the numerical and the measured results concerning the strain responses.

2002 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yoshihito Suzuki ◽  
Shoichi Kido

The stress variations in butt adhesive joints of dissimilar hollow cylinders under impact tensile loadings are analyzed in elastic and elasto-plastic deformation using a finite element method. The FEM code employed is DYNA3D. The effect of Young’s modulus of the adhesive, adhesive thickness and the inside diameter of the hollow cylinders and Young’s modulus ratio between dissimilar adherends on the stress variations at the interfaces are examined. In addition, a process in rupture at the interface of the joint is analyzed. The stress distributions in the joints under static loadings are also analyzed by an FEM. The characteristics of the stress variations in the joints under impact loadings are compared with those in the joints under the static loadings. Also, the joint strenths under impact loadings are estimated. As the results, it is found that the maximum value of the maximum principal stress σl occurs at the outside of the interface. It is also found that the maximum principal stress σl at the interface decreases as the inside diameter of the hollow cylinders increases. The characteristics of the joints subjected to the impact loadings are found to be opposite to those subjected to the static loadings. In addition, the experiments were carried out to measure the strain response of the butt adhesive joints under impact tensile loads using strain gauges. Furthermore, the joint strengths under impact loadings were measured. Fairly good agreements are observed between the numerical and the measured results.


Author(s):  
Toshiyuki Sawa ◽  
Kohei Ichikawa

The stress variations and stress distributions in stepped-lap adhesive joints of dissimilar adherends under impact tensile loadings were analyzed in elastic range using three-dimensional finite element method. The impact loadings were applied to the lower adherend by dropping a weight. The stress distributions in stepped-lap adhesive joints of dissimilar adherends under static tensile loadings were also analyzed using FEM. The effects of Young’s modulus of the adherends, the adhesive thickness and the number of butted steps of adherents ware examined under both impact and static loadings. As the results, The maximum value of stress σ1 increased as Young’s modulus of the adherends increased for the impact loadings. The maximum value of stress σ1 increased as the numbers of steps in the adherends increased for the static loadings. In addition, the experiments to measure the strain response of joints subjected to impact tensile loadings were carried out using strain gauges. A fairly good agreement was found between the numerical and the measured results concerning the strain responses.


Author(s):  
Toshiyuki Sawa ◽  
Masahiro Sasaki

The stress variations and stress distributions in scarf and stepped-lap adhesive joints of similar adherends under static and impact tensile loadings were analyzed in elastic range using three-dimensional finite element method. The impact loadings were applied to the lower adherend by dropping a weight. The stress distributions in scarf adhesive joints of similar adherends under static tensile loadings were also analyzed using FEM. The effects of Young’s modulus of the adherends, the adhesive thickness, and the angle of the adherends on the stress distributions at the interfaces between the adherends and the adhesive were examined under static loadings. The maximum value of σ1 decreased as young’s modulus of the adhesive increased in the stepped-lap adhesive joints under static loadings. However, the result of the scarf adhesive joints under static loadings was opposite to the above result. The value of σ1 became minimum when the scarf angle was 52°in the scarf adhesive joint. In addition, the experiments to measure the strain response and strain of joints subjected to impact and static tensile loadings were carried out using strain gauges. Fairly good agreements ware found between the numerical and the measured results.


2000 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Takahiro Ohmori

Abstract The stress wave propagation and the stress distribution in stepped-lap adhesive joints of similar adherends subjected to impact tensile loads and elastic deformation are analyzed using three-dimensional finite-element method (FEM). The impact load is applied to the joint by dropping a weight. One end of the upper adherend is fixed, and the other end of the lower adherend is subjected to an impact load. FEM code employed is DYNA3D. The effects of Young’s modulus of the adherends, the number of lapped steps, and the adhesive thickness on the stress wave propagation at the lapped, and fee butted interfaces are examined. It is also found that the maximum value of the maximum principal stress σ1 occurs at the end of the butted interface between the adhesive and the lower adherend to which the impact load is applied. As the number of the lapped steps increases, the maximum value of the maximum principal stress σ1 increases. It is found that the maximum value of the maximum principal stress σ1 increases as the adhesive thickness decreases. The maximum value of σ1 increases as Young’s modulus of the adherends increases. In addition, the experiments were carried out to measure the strain response of stepped-lap adhesive joints subjected to impact tensile loads using strain gauges. A fairly good agreement is seen between the analytical, and the experimental results.


Author(s):  
Toshiyuki Sawa ◽  
Yoshihito Suzuki ◽  
Shoichi Kido

The stress variation in butt adhesive joints of hollow cylinders subjected to impact bending moments was analyzed in elasto-plastic deformation ranges using finite element method. The impact bending moments were applied to the loading side adherend of the joint by dropping a weight. The name of FEM code employed was DYNA3D. The effects of Young’s modulus of the adhesive and the effect of the adhesive thickness on the stress variations at the interfaces were examined. In addition, the characteristics of joints subjected to the impact bending moments were compared with those of the joints under static bending moments, and the strength of the joints under impact bending moments was estimated by using the interface stress distributions. As the results, it was found that (1) the maximum value of the maximum principal stress σ1 occurred at the outside edges of the fixed side adhesive interface under the impact bending moments; (2) The maximum value of maximum principal stress σ1 increased as Young’s modulus of the adhesive increased when the joints were subjected to impact bending moments; (3) The maximum value of σ1 increased as the adhesive thickness decreased; (4) the characteristics of joints subjected to the impact bending moments were opposed to those subjected to the static bending moments. In addition, experiments were carried out to measure the strain response of butt adhesive joints subjected to impact bending moments using strain gauges, and the joint strengths were also measured. The measured strain response was compared with the numerical results. A fairly good agreement was found between the numerical and the measured results concerning the strain responses.


Author(s):  
Toshiyuki Sawa ◽  
Yuya Hirayama ◽  
He Dan

The stress wave propagation and stress distribution in scarf adhesive joints have been analyzed using three-dimensional finite element method (FEM). The FEM code employed was LS-DYNA. An impact tensile loading was applied to the joint by dropping a weight. The effect of the scarf angle, Young’s modulus of the adhesive and adhesive thickness on the stress wave propagations and stress distributions at the interfaces have been examined. As the results, it was found that the point where the maximum principal stress becomes maximum changes between 52 degree and 60 degree under impact tensile loadings. The maximum value of the maximum principal stress increases as scarf angle decreases, Young’s modulus of the adhesive increases and adhesive thickness increases. In addition, Experiments to measure the strains and joint strengths were compared with the calculated results. The calculated results were in fairly good agreements with the experimental results.


Author(s):  
Toshiyuki Sawa ◽  
Toshimasa Nagai ◽  
Takeshi Iwamoto ◽  
Hideaki Kuramoto

Adhesive joints in mechanical structures are subjected to static loading as well as impact loading. It is desired for the adhesive joints to have sufficient strength under both static and impact loadings. A lot of studies on the adhesive joints and the joint strength subjected to static loading have been carried out and examined. A few research works on the adhesive joint subjected to dynamic loading have been done, however, it has not fully elucidated for applying the joints to important sections in mechanical structures. In this study, the impact strength of adhesive joints subjected to impact shear loading is investigated using modified split Hopkinson pressure bar (SHPB) apparatus. The shear strength of adhesive joint, in which a solid cylinder is bonded to a hollow cylinder by an adhesive, is determined from maximum applied shear stress. A commercial thermosetting epoxy adhesive is used in the experiments. At the same time, the stress distributions in the joints subjected to impact shear loading are simulated by the finite-element analyses (FEA). The effect of adhesive thickness is investigated experimentally and computationally. It is shown that the strength is greatly affected by the adhesive thickness and the effect on the stress distributions in the joint is discussed.


Author(s):  
Ryo Nogaito ◽  
Toshiyuki Sawa ◽  
Atsushi Karami

Stress distributions in adhesive-rivets combination joints subjected static bending moments are calculated using three-dimensional finite-element calculations. The stress propagation and stress distribution subjected to impact bending moments are also calculated using three-dimensional FEM calculations. In the FEM calculations, the effects of number, position and diameter of rivets, and Young’s modulus of the rivet on the stress distributions at the adhesive interface are examined from fail-safe design standpoints. From the FEM results, the maximum value of peel stress decreases as the position of rivets in the axial direction is decreased and the position of rivets in the width direction increases in the joints with two and four rivets. It is also found that the results on the stress distributions in the joints under the static bending moments show the same tendency of the joints under the impact in-plane bending moments. Concerning the effect of Young’s modulus of the rivet, it is not seen on the peel stress under the static in-plane bending moments. For the verification of the FEM calculations, the experiments were carried out to measure the strain response under both static and impact load conditions. Fairly good agreements are observed between the FEM calculations and the measured results.


Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 328
Author(s):  
Kamil Anasiewicz ◽  
Józef Kuczmaszewski

This article is an evaluation of the phenomena occurring in adhesive joints during curing and their consequences. Considering changes in the values of Young’s modulus distributed along the joint thickness, and potential changes in adhesive strength in the cured state, the use of a numerical model may make it possible to improve finite element simulation effects and bring their results closer to experimental data. The results of a tensile test of a double overlap adhesive joint sample, performed using an extensometer, are presented. This test allowed for the precise determination of the shear modulus G of the cured adhesive under experimental conditions. Then, on the basis of the research carried out so far, a numerical model was built, taking the differences observed in the properties of the joint material into account. The stress distribution in a three-zone adhesive joint was analyzed in comparison to the standard numerical model in which the adhesive in the joint was treated as isotropic. It is proposed that a joint model with three-zones, differing in the Young’s modulus values, is more accurate for mapping the experimental results.


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