Metals used as cap for containers preserve liquids in the bottles, but the dumping of caps particularly soft drink bottle caps are harmful for the environment. On the other hand, concrete has low tensile strength and to offset this problem some fiber like material can be added to concrete to increase its tensile strength. Hence, an effort was made in the present investigation to study the influence of addition of waste materials like soft drink bottle caps at a dosage of 0.5%, 1% and 1.5%, of total weight of concrete as fiber. In this study, caps were cut into strips of size of 3 mm width and 10 mm length. Experimental investigation was carried out adding bottle caps in concrete and tests were carried out as per recommended procedures by relevant codes. The experimental values such as compressive strength and split tensile strength were found to be increased. The most improved compressive strength and split tensile strength were found for 1% bottle cap fiber. The strengths were increased by maximum 22.98% and 23.14% respectively.
The fatigue limit and crack growth behavior of slit specimens of carbon fiber reinforced epoxy composites were investigated. The fatigue limit was defined by the maximum stress amplitude that the specimen endured 106 times repeated stress when S-N curve was used. The highest fatigue limit was obtained when all the fiber directions were parallel to the load axis. The fatigue limits were evaluated in the cases of composites using alternately parallel and perpendicular to the load axis and compared with the result of the specimen having all the carbon fiber orientations were parallel to the load axis. When the measured value of the fatigue limit was lower, shear damage to the epoxy resin and peeling of fiber from epoxy resin occurred clearly. According to those results, it was expected that the fatigue limit of smooth specimens of carbon composites with long fibers can be evaluated from the results of the slit specimens.
Abstract-A method for detecting the application of an unexpected dangerous load was investigated. An acceleration behavior of crack growth due to the application of overload and or underload during fatigue crack growth test with constant stress amplitude was observed. In some cases, the acceleration of crack growth brings catastrophic failure in machine structure. Therefore, it is useful for machine maintenance to know whether an unexpected load was applied or not by doing a daily inspection. In the present study by using center-crack specimen, a simple method of detecting the application of overload or underload was investigated. Such an unexpected load can be detected by the waveform of the function of stress and strain in the vicinity of the crack.
The fatigue limit and fracture behavior of epoxy carbon fiber reinforced composites and hybrid composites were investigated. An aluminum foil and thin aluminum plate were incorporated with the carbon fiber to make the hybrid reinforced composites. Several specimens were prepared, and a series of tests were carried out to investigate the fatigue life and fracture behavior. Then the results were compared among epoxy carbon fiber reinforced composites and the hybrid composites. It is discussed whether the S–N curves shows almost the similar characteristics of these two types of hybrid composites or not. As far as the present result, the stress ratio and the type of hybrid composites effect on the fatigue life. The interfacial bonding plays an important role in the strength and fracture behavior of notched specimen of the fabricated composites.
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