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The bending test is one of the most important tests that demonstrates the advantages of functional gradient (FGM) materials, thanks to the stress gradient across the specimen depth. In this research, the flexural response of functionally graded polymeric composite material (FGM) is investigated both experimentally and numerically. Fabricated by a hand lay-up manufacturing technique, the unidirectional glass fiber reinforced epoxy composite composed of ten layers is used in the present investigation. A 3-D finite element simulation is used to predict the flexural strength based on Hashin’s failure criterion. To produce ten layers of FGM beams with different patterns, the fiber volume fraction ( Vf%) ranges from 10% to 50%. A comparison between FGM beams and conventional composite beams having the same average Vf% is made. The experimental results show that the failure of the FGM beams under three points bending loading (3PB) test is initiated from the tensioned layers, and spread to the upper layer. The spreading is followed by delamination accompanied by shear failures. Finally, the FGM beams fail due to crushing in the compression zone. Furthermore, the delamination failure between the layers has a major effect on the rapidity of the final failure of the FGM beams. The present numerical results show that the gradient pattern of FGM beams is a critical parameter for improving their flexural behavior. Otherwise, Vf% of the outer layers of the FGM beams, i.e. Vf% = 30, 40, or 50%, is responsible for improving their flexural strength.

In this study, the effect of clamping force on the bolted double-lap joints has been investigated experimentally. The mechanical behavior of the present joint has been divided into several stages based on the sequence of failure. The commencement failure occurred in such joint is the sticking failure, i.e., loose of clamping effect. One of the main objectives of present investigation is to study the effect of tightening torque value (T = 0-30 Nm) on the sticking failure load, i.e., initiation of the relative sliding. Three different geometries (e/D = 1, 2, and 3) have been adopted to get different modes of failure, namely bearing, shear, and tensile. A steel sheet AISI 1006 with fixed width 30 mm and thickness 3 mm was used. The present experimental results showed six different stages identifying the mechanical behavior of the doublelap joint namely; sticking failure, bearing failure, shearing failure, ultimate strength, tensile/shear crack initiation (depending on the value of e/D), and lastly final failure. For e/D = 2 and 3, the maximum value of sticking failure load is obtained at T = 25 Nm, while T = 30 Nm for e/D = 1. Furthermore, for all values of e/D, the values of sticking failure load are approximately the same at T = 30 Nm. In the case of small values of tightening torque (T \ 25 Nm), the stiffness of the joint before sticking failure increased by increasing the value of e/D and T. The difference between the stiffness of joints with different values of e/D, e/D = 1-3, decreased by increasing the tightening torque.

The holy Quran, from more than 1400 years, told us that Zul-karnain had made a metallic composite material between iron and copper [1,2] as follows: “Bring me sheets of iron” — until, when he had leveled [them] between the two mountain walls, he said, “Blow [with bellows],” until when he had made it [like] fire, he said, “Bring me, that I may pour over it molten copper * So Gog and Magog were unable to pass over it, nor were they able [to effect] in it any penetration.”: Translation of verses 96 and 97 in Surah Al-Kahf (18), The holy Quran [3]. According to the above story, the matrix is copper, while reinforcement is iron of this metal matrix composite. The present paper is going to investigate the Metal-Matrix Composite Material (MMC) suggested by Zul-karnain at different manufacturing conditions by using the experimental method. The effect of reinforcement temperature on the integrity of such MMC is one of the main goals of the present work. The mechanical behavior of the present QMMC is also examined in the present research as preliminary study. Furthermore, the finite element method is used to predicate the debonding force of MMC based on Virtual-Crack-Closing-Technique (VCCT).

This paper aims to assess experimentally the mechanical and tribological behavior of conventional and functionally graded (FG) polymeric matrix composites reinforced with continuous glass fibers. The small punch test (SPT) and a pin-on-disc device were used in the present work to examine the mechanical and wear behavior, respectively. The hand lay-up technique was used in the present investigation to manufacture the conventional and FG composites. Various wooden looms with different nailed spacing were employed to manufacture the FG composites. According to test type, the FG composite is composed of four and ten layers, with a different glass fiber volume of fraction (Vf%) for each layer. In addition, the finite element simulation based on Hashin’s failure criterion and cohesive zone modeling was used to show the progressive failure and give more explanation regarding the flexural behavior of such composites. The present results indicate that the wear rate of an FG composite could be affected by many factors, including the disk speed, applied load, the composite layers number, and average glass fiber volume fraction. On the other hand, the arrangement of layers in the composite materials by variation of Vf% for each layer can improve the wear rate and value of the ultimate load before the fracture of the composite material when subjected to SPT. The experimental and numerical results for all SPT specimens showed that the fracture of the SPT specimens began beneath the punch tip and grew along the fiber direction. The ultimate flexural capacity of FG composites increased by 30% compared with the conventional composites.