Papers by Keyword: Four Point Bending Test

Abstract: Fatigue, creep and erosion are among the factors which destroy the asphalt mixture and modifying the asphalt binder via additives such as crumb rubber, sulfur, carbon, as well as natural and synthetic polymers has been done in order to improve the strength of asphalt mixture. Knowledge in the field of nanotechnology along with its capability and attractiveness for application as nanoparticles in different industries such as asphalt industry has attracted great attention in recent years. In this study, specific percentages of TiO₂ nanoparticles, namely 2, 4, and 6, were added to the asphalt binder as the nanocomponent. Done physical common tests such as penetration degree, softening point, flash point and viscosity of the base asphalt binder and modified asphalt binder, the bending beam samples composed of origin asphalt sample and modified asphalt sample with 4% TiO₂ nanoparticle were subjected in different micro strains to fatigue loads. Results of four point bending fatigue test showed that the addition of TiO₂ nanoparticles to the asphalt binder increased the fatigue strength in the asphalt samples. Modified asphalt binder is stiffer, more viscous than original asphalt binder and due to TiO₂ nanoparticles more temperature tolerance and load bearing capacity, modified Asphalt is more resistant under fatigue loads.

Abstract: For the compressive strength of the normal concrete is high and the tensile strength is low, it is typically brittle material. The ultimate tensile elongation of it is insufficiently 1/1000. Zhongwei Wu, an academician of Chinese Academy of Engineering pointed out that compounding cementitious composites was the way to make it high-performance, and fiber reinforced was the key^[1]. Polyvinyl Alcohol Engineered Cementitious Composites has super flexural performance^[2] and stretching ability^[3],and its ultimate deflection is approximately 40 times larger than that of normal concrete when bended, similar to the multiple cracking and super toughness of uniaxial tensile test, it shows significant bending hardening behavior in the process of the test. This paper studied its flexural property by four point bending test .

Abstract: The mechanical behavior of oxidized low alloyed steel has been studied at temperatures between 700°C and 900°C. Such a work is carried out to obtain information about the damages which occur in the oxide scales developed on steels during hot rolling process. Actually the mechanical behavior is tested with a four point bending apparatus at high temperature under controlled atmosphere. Some information about mechanical damages have been collected during the mechanical loading thanks to recording of the sample acoustic emission. During this study, two procedures have been used which differ in the thermal scheme used to build the oxide scales. The results obviously show that the procedure has a great influence on the mechanical behavior of the oxidized low alloyed steel. For instance a marked decrease of the stress is observed at constant displacement between the 900°C and 800°C tests of one procedure, as the opposite behavior is observed with the other procedure. Different points are considered to explain such results, as the thermal strains which are only present in one of the two procedures, the phase transformations in the metal and in the oxide.

Abstract: Four point bending tests have been carried out on a thermal barrier coating (TBC) system, at room temperature. The TBC system consisted of a plasma sprayed Y-TZP top coat with 8 % in weight of Yttria, a bond coat of NiCrAlY and a Ni-based superalloy Inconel 625 as substrate. The TBC coating was deposited on both sides of the prismatic specimens. Efforts have been done in detecting the damage of the coating by means of Maltzbender et al [1] model.

Abstract: In order to perform elastic-plastic fracture mechanical analyses, fracture resistance curves for concerned materials are required. A standard CT specimen was used to obtain fracture resistance curves. However the fracture resistance curve by the standard CT specimen was very conservative to evaluate the integrity of the structure. Also the fracture resistance curve was affected by the specimen geometry, crack plane orientation, reverse cyclic loading and dynamic strain aging. The objective of this paper is to be certain the conservativeness of the fracture resistance curve by the standard CT specimen. For these purpose, fracture tests using the real-scale pipe specimen and standard CT specimen test were performed. A 4-point bending jig was manufactured for the pipe test and the direct current potential drop method was used to measure the crack extension and the length for the pipe test. From the result of the pipe and the standard CT specimen tests, it was observed that the fracture resistance curve of the standard CT specimen test was conservative compare to that of the pipe specimen test.