The use of structural Adhesives in automotive structures has been increased recently for their role in noise, vibration and harshness (NVH). Therefore, the dynamic behavior of structures containing bonded Joints has become an area with numerous investigations over the past decades. Development of accurate formulations capable of representing Adhesively bonded Joint dynamics is a step forward in constructing the numerical models for one of the most useful kinds of Joints in industry. Analysis of the Adhesive layer between the two parts requires special assumptions which leads to using nonlinear and three dimensional models. Obtaining shape functions for an Adhesive element by using finite element (F. E. ) theory is a complicated and difficult task to do. The complexity is increased when it is assumed that the Adhesive element is compatible with the plate element. In this paper, a new finite element formulation is developed for the Adhesive layer which does not rely on shape functions and is compatible with the plate element. The accuracy of the proposed element is evaluated by using numerical and experimental results.

Hypothesis: Adhesives and sealants based on modified silane polymer (MS polymer) are increasingly gaining market share in Adhesive and sealant market place due to their desirable performance in various applications. Methods: In order to find the most optimal Adhesive processing parameters, different stages of aluminum surface treatment in three stages were investigated, including the surface degreasing, sanding and priming. In this manner, the performance of four different types of degreasing agents and two kinds of silane-based primers were investigated individually. The optimum bond line thickness was also determined through Adhesive Joint shear strength. The effect of different degreasing agents and silane-based primers were evaluated through lap-shear strength. The effect of Adhesive layer thickness was studied through lap-shear strength and cleavage strength tests. Findings: Optimum bond line thickness was determined at 0. 5 mm based on the results of the Adhesive shear strength, whereas the results of the fracture toughness indicated 1. 25 mm as the optimum Adhesive layer thickness. The lower Adhesive strength in thicker bond lines may well be due to the possible formation of air traps and lower constrained effect of the substrate. Therefore, the least requirements for aluminum surface treatment was surface degreasing followed by sanding which results in a transition from Adhesive fracture mode to cohesive fracture. The use of two kinds of silane-based primers containing the amine group, triethoxy silylpropylamine (APS) and the other with epoxy group, glycidoxypropyl trimethoxysilane (GPS) was more efficient in improving Joint durability even after 2500 h cyclic aging with the more pronounced results for the APS.

Adhesive bonding technology is being used in a variety of modern industries, including the automotive, aerospace, maritime, construction, defense and so on. On the other side, polymeric nano-composites attracted both academic andindustrial interests in the past decades. The scope of this paper is experimental investigation on the effects of theaddition of Alpha-alumina nanoparticles to the woven glass / epoxy composite and Araldite 2015 Adhesive on themechanical properties of the composite Adhesive bonded Joints. In this study, vacuum assisted resin transfer moldingwas used to fabricate experimental samples and to fabricate composite samples, 6 glass-fiber layers with a surfacedensity of 200 g/m2 were used. The study of the influences of the addition of Alpha-alumina nanoparticles withdifferent weight ratios to glass/epoxy composites suggests that the maximum values of the ultimate strength, elongation, toughness, and Young’ s modulus belong to the samples with the weight ratios of 0. 43, 1, 1, and 2. 1%, respectively. The experimental results from the shear tensile test show that the incorporation of 0. 74 wt% ofnanoparticles to the Adhesive increases the Joint strength by about 14%.

This study investigates the effect of mixed Adhesive having different modulus on single lap Joint and also under peel test. The study compares these Joints with that of corresponding Joint containing single Adhesive under two loading rate of 5 and 100 mm/min and three temperature range of room, 100oC and 200oC. Five types of Adhesives were used in this assessment namely: silicon, epoxy, mixed epoxy-silicon, epoxy toughened with liquid rubber (CTBN), mixed epoxy toughened with liquid rubber (CTBN)–epoxy. Result indicated better shear strength performance by mixed epoxy-silicon Adhesive Joint in the single lap shear at both loading speed followed by epoxy and liquid rubber modified epoxy Joints. Similar assessment under the three temperature range also revealed better retention of shear strength for the mixed epoxy-silicon Adhesive Joint in particular at 200°C. This result revealed about 65 percent reduction in strength for epoxy Adhesive as against 31 percent reduction for the mixed epoxy-silicon Adhesive. Peel tests showed unstable peeling behavior in all Joints except Joint with rubber modified epoxy toughened Adhesive Joint. Further assessment of peel test results showed both mixed Adhesives i.e. mixed epoxy-silicon, epoxy toughened with liquid rubber (CTBN), mixed epoxy toughened with liquid rubber (CTBN) -epoxy had higher peel strength compared to the other Adhesive Joint tested.

In this paper, the influencing factors on hybrid Adhesive-riveted Joints were investigated. For this purpose, first a finite element model was validated based on experimental results, then the effects of influencing material and geometrical factors on the strength of the hybrid Joints were studied using the explicit finite element analyses. The numerical model was able to simulate damage in the Adhesive layer and in the rivets. The results showed that in a hybrid Adhesive-riveted Joint, it is better to position the rivets where a minimum reduction in the Adhesive Joint due to the rivet holes obtained i.e. as far as possible from the Joint ends. This is in contrary to the riveted Joints in which placing the rivets closer to the Joint ends resulted higher Joint strength. In general, incorporating rivets in an Adhesive Joint for manufacturing a hybrid Joint can result higher or lower Joint strength in comparison with the Adhesive Joint in different conditions that were studied in this research. It should be noted that in case that a low-strength Adhesive is utilized in a hybrid Adhesive-riveted Joint then placing the rivets closer to the Joint ends can results higher strength for the Joint similar to the riveted Joints.

In this research, the transient shear stress distribution in an Adhesive Joint due to fiber breakage has been investigated. Transient stress is a dynamic response of the Joint to the fiber discontinuities till their static equilibrium state. To study this behavior, equations governing the motion of fibers in the matrix, due to their breakage, are derived and the effect of number of broken fibers is studied on transient response of the structure. Shear lag model is used to extract fiber displacement. The equilibrium equations are solved using the explicit finite difference method. The effect of fiber materials and Adhesive thickness is also studied on stress distribution. Results show that for an increase in the number of broken fibers, the stress concentration in the composite structure increases. Moreover, the shear stress created in the matrix and the Adhesive layer is reduced with an increase in fiber elastic modulus, such that for glass and graphite fibers (E=74 and 130 GPa respectively), the maximum shear stresses in the Adhesive are 0.861 and 0.461 MPa, while in the adherends, they are equal to 3.192 and 2.409 MPa respectively.

In this research, numerical and experimental investigations were performed to study the effect of the Adhesive Joint on the fractural behavior of the grid-stiffened composite plates. Foam format was designed to construct two samples of lattice composite plates, and the hand layup technique was used to prepare the ribs. Finally, the obtained ribs were connected to the composite shell in the interface of ribs with shell using Axson H9940 BK for first sample and LR520 resin Adhesives for second sample. The prepared samples were analyzed using the three-point bending test. For this purpose, a test fixture was designed and constructed. The standard test of the crack release energy in the first and second mode, tensile test, and nol test were performed to evaluate the mechanical properties of the carbon cloth, carbon fibrs, resin, and Adhesive. The numerical solution of the problem and comparing the obtained results with experimental data revealed that the Axson Adhesive connections can tolerate more force in comparison with resin Adhesive connections before structure destruction.

Statement of Problem: A few studies have been conducted about bioglass posts.Aim: The aim of this study was to compare bioglass posts with prefabricated metallic posts in clinical performance of extensive composite restorations for anterior endodontically treated teeth.Materials and Methods: Sixty endodontocally maxillary anterior teeth, with horizontally or vertically destruction were selected. Teeth were divided into two groups based on the kind of post: Metallic prefabricated parapost and bioglass post. Each group was divided into three subgroups based on anterior bite: normal, deep bite and edge to edge. Gutta-percha was removed from 2/3 of canal length for parapost and 1/3 for bioglass post. After etching with phosphoric-acid (37%) and applying dentine bonding Syntac, Duo cement was used for the adhesion of bioglass post and a self cured composite (Degufil) for parapost. Restoration was done with a hybrid composite (Heliomolar). Follow up studies, radiographically and clinically, were done every three months for a 1.5-year period. Exact Fisher and Pearson tests were used for data analysis.Results: Apical lesion was not observed in any of the radiographs. Post seal was increased by resin cement and dentin bonding agent. Post type did not significantly affect on the clinical success rate of the restorations. The retention of restoration, for both posts, was the same. Crown destruction had no significant effect on success rate. The type of anterior bite had a significant effect on success rate, as the total 6.6% failure rate was related to the patients with anterior deep bite.Conclusion: It is suggested to use metallic paraposts and bioglass posts, in extensive composite restorations for patients with deep-bite, more conservatively.

In this research, the design, fabrication and testing of a single L-shaped Adhesive Joint between a composite sheet and an aluminum piece under tensile loading has been performed experimentally. To make an experimental sample, nanographene with different weight percentages was used to strengthen the composite and also structural Adhesive (homogeneous with the composite phase phase resin) was used to improve the mechanical properties of the Joint. The effect of changing the base length of the L-shaped aluminum part on the bond strength has also been investigated. 12 bonding modes with a combination of weight percentages of 0. 1 and 0. 3 for multilayer and weight percentages of 0. 1, 0. 3 and 0. 5 for Adhesive with 5 repetitions in each test, a total of 60 The sample is made and examined. By comparing and examining the results of the tensile test of samples and photographs taken by scanning electron microscopy (SEM) of the separation of multilayer and L-shaped piece at the separation site, it was found that the connection with a combination of zero weight percentage for multilayer and weight percentage of 3 / 0 for Adhesive has shown the maximum tensile strength. This means that the addition of nanographene to the multilayer reduces the tensile strength and the addition to the epoxy resin as an Adhesive improves the tensile strength of the Joint. Finally, the effect of increasing the length of the overlap area of ​​the two Adhesive pieces was investigated. The result of the combination of the optimal percentage of nanographene in the multilayer and the Adhesive showed that a 25% increase in the length of the overlap area would increase by 148% and a 50% increase in the length of this area would result in a 200% increase in the vertical tensile force borne by the Joint.