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The present research deals with the impact response of notched aluminum plates repaired by fiber metal laminate (FML) patches under various temperatures using drop weight impact test status. Some aluminum samples repaired by FML patches were prepaired to study their impact behavior and frcture mechanisms under drop weight tests at the temperature range of -20 ℃ to 60 ℃. An Energy Profiling Diagram (EPD) was used to obtain the penetration and perforation thresholds of hybrid composites. Besides, the effect of temperature on some impact characteristics such as endurance load, contact time and permanent deflection were also studied. The results showed that the amount of force for nearly all of the samples increased by increasing of the room temperature. The ability of energy absorption of the samples was also the most at the room temperature, therefore the energy thereshold of samples increases by increasing of the room temperature. Temperature variation also affects on the impact characteristics of composites patches and in some cases results in a 20 percent reduce in impact strength of the samples. It was also shown that the most value of impact parameters reaches at -20 ℃ and 60 ℃.

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Thermal Barrier Coatings are used as thermal protective of parts using under high temperature circumstance. These coatings usually include three layers respectively: ceramic top coat, grown oxide layer and bond coat. Due to manufacturing process and special structure of thermal barrier coatings, failure mechanisms of these coatings are affected by applied loads on coated part. In this paper failure of these coating under thermal fatigue was studied numerically and experimentally. A specimen of Inconel 617 which were coated by air plasma method and it was tested in a test setup with capability of applying four point bending load, under thermal fatigue experiment with the maximum temperature of 1170 oC in addition to constant bending load with the magnitude of 7500 Nmm. Thermal fatigue test was contined until coating spallation and temperature of specimen surfaces was measured during the test. Finite elements modeling was performed by ABAQUS to simulate the experiments thermal and mechanical loading conditions with using cohesive zone model to model top coat delamination and failure. Finally with a little change in the model, was attempted to adapt the bending magnitude of the specimen from model on experiment result to estimate interfacial cohesive properties for these coatings from finite elements results.

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Structures during their lifetime experience plenty of static and dynamic loads. These loads cause failure or undermine the structures. So, reinforcement or repairing failed parts is one way to repair out of service structures. Composite materials have been used to reinforce structures. These materials enjoy advantages such as the proportion of their strength to their weight. As these structures get exposed to some load a number of failures get introduced. This research investigates the failure mechanisms of a notched 2024-T3 aluminum plate repaired with a composite patch using visual and acoustic emission methods. After constructing the specimens, tensile test has been conducted, and acoustic emission sensors have been stocked on the surface of the plate, so that they can record acoustic data. At the first stage, mechanical data obtained from the specimens in different states based on the number of layering have been analyzed. At the second stage, acoustic data, obtained from recording of acoustic emission signals, have been compared with the mechanical data. Also the images obtained from SEM were used to investigation of damages. According to this research, it is identified that a reasonable correspondence between the results obtained from mechanical and acoustic data and the desired functionality of the acoustic emission method in determining failure mechanism in those specimens that are repaired with composite patches.

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Thin-walled composite structures are increasingly used in vehicles where light weight and high energy absorption capacity are important. Fiber reinforced composites, such as glass/fiber reinforced polymers, have attracted attention in automotive engineering due to their properties such as light weight and high mechanical properties. Fiber reinforced composites use the energy in various ways to damage their structure, which in terms of structural failure; delamination, fiber breakage, and matrix cracking are the predominant conditions. According to the literature, design parameters and optimal dimensions of glass/epoxy composite tubes were determined. After that, by using experimental testing, acoustic emission technique, and finite element method, various failure mechanisms of 45 ° filament wound composite tube were investigated. Examination of failure by acoustic emission method showed that the predominant mechanism for 45 ° samples is fiber breakage. In order to simulate the behavior of the samples, the VUMAT subroutine was used with the help of 3D Hashin criteria for the onset of damage and the continuous damage criterion was used to simulate the spread of failure. The agreement of the obtained experimental diagrams with the subroutine developed for the composite simulation confirmed the ability of the model to predict the behavior of the composite sample even after the maximum tolerable force. By comparing the force-displacement diagrams with the energy data obtained from the acoustic emission method, it was found that the acoustic emission method can be used to predict the behavior of composite pipes under lateral loading.