Papers by Keyword: Shear Test

Abstract: Solid-state diffusion bonding (DB) of Copper-Copper (Cu/Cu) was carried out under varying bonding parameters (time and temperature) in argon shielding gas environment. Initially, the bonding was performed at bonding temperatures of 800, 850, and 900 °C for 60 minutes. Secondly, the bonding was carried out at holding times of 90, 120, and 150 minutes at 900 °C. The microstructural and mechanical properties of the bonding interface were evaluated via lap shear and micro hardness tests, X-ray diffraction, and Optical microscopy. It was found that the optimal bonding parameters for the joint interface was 950 °C for 150 minutes, resulting in maximum shear strength of 133 MPa. The X-ray diffraction also shows the formation of solid solution of Cu without the formation of any intermetallic compounds (IMC). The micro hardness test revealed a maximum hardness of 89 HV at the joint interface. Optical microscopy shows the formation of voids at the joint interface take place due to the Kirkendall effect, which increased with higher temperatures for longer time, and cause a wide diffusion-affected zone (DAZ).

Abstract: This work evaluates the shear stress in concrete beams with the addition of reinforcing fibers. Since there is no established standard in Peru, it was proposed to use the "JSCE-SF6" test method recommended by the Japanese Society of Civil Engineers and an analytical model to determine the shear strength of concrete with fibers. For this purpose, steel and polypropylene fibers were used in the proportions of 3kg, 5kg, 7kg and 9kg for each design. The main test was the shear test based on Japanese standards, however, secondary tests such as compression and flexural tests were also performed. The results obtained showed the contribution of the fibers in the three tests performed. In the shear test, the polypropylene fibers obtained a higher shear strength in all their mix designs in the same proportions. Additionally, an analytical model is proposed to determine the shear stress in concrete with fibers, which includes as variables the compressive strength, the mass fraction of fibers and the tensile strength of the fibers, which generates acceptable values close to those obtained experimentally with the Japanese Standard Shear Test.

Abstract: A welding test piece has been made by the overlap friction stir welding (FSW) of 400 mm x 110 mm x 1 mm sheets of EN AW 5754 aluminium alloy, placed on a tilted jig, of the multifunctional friction processing machine, type MMPF.

Abstract: This paper aims at investigating the matrix-to-textile stress transfer in a fabric reinforced cementitious matrix FRCM system, not bonded to any substrate, under shear loads. To this end, direct shear tests are performed on a basalt FRCM specimen introduced into an innovative properly designed four-hinge frame loaded by a universal testing machine. The role of the single components in the global shear behavior of the FRCM is experimentally analyzed. Digital image correlation (DIC) is adopted for evaluating both the displacement and strain fields as well as for detecting the damage. Furthermore, the shear response of the tested FRCM material is reproduced via an effective numerical approach that considers the nonlinear behavior of the mortar and the possible micro-mechanisms that arise between the textile and the matrix, introducing suitable interfaces joining the FRCM constituent layers, i.e. textile and mortar layers. Experimental outcomes highlighted the non-negligible influence of the matrix in the shear response of the composite, both in strength and stiffness. The proven DIC technique demonstrated to be suitable also for this novel test type, since it allows to obtain shear strains, location and amplitude of cracks with satisfying accuracy, such as to make direct shear tests results a benchmark to be used for numerical simulations. Numerical analyses are performed in order to verify the efficiency of the proposed model in reproducing the mechanical behavior of FRCM composites under shear loads and in describing the damage patterns during the loading process.

Abstract: On 3DPC, the layers are made through a process where the cement mortar is extruded through a nozzle that follows a predetermined circuit. The classic method of formwork generates a uniform element, while 3D printing generates a non-homogeneous element. Such an innovative process offers new horizons to explore. One of these is the cohesion between the two printed layers and all their mechanical properties. The objective of this work is to study the shear action of two printed layers. To understand the mechanisms, the tested specimens were made in four different ways. The first using a formwork made for the occasion. The second way involves the creation of a printed specimen with a continuous printing path. The third has a time interval of about an hour between the second and third layer. The fourth also has an interval of one hour between the same layers with the addition of a special additive mortar used for the casting recovery. The results obtained reflect on the differences between different specimens and regulations. The differences between the specimens that are studied concern the single printed specimens, the formwork specimens and the printed ones. At a regulatory level, the results of the printed specimens are compared with the regulations concerning the same tests carried out on specimens made of masonry and mortar.

Abstract: Abstract. Masonry strengthened with natural fabric-reinforced cementitious matrix (NFRCM-strengthened masonry) is investigated by updating an existing discrete element model. Masonry walls are modelled by rigid blocks and elastoplastic interfaces that are able to account for mortar joints and block cracking. The reinforcement is modelled in a simplified manner considering perfect adhesion between wall and reinforcement and by adopting further spring elements connecting block centres. The model is validated by comparing it with an existing FEM based on a multi-step homogenization, where reinforced masonry is considered as a whole. Both approaches are used for performing nonlinear pushover tests with an increasing shear action applied to unreinforced and reinforced panels. The updated discrete model turns out to be able to represent the strength increment given by the reinforcement, but it is less able to represent the corresponding ductility increment.

Abstract: Fiber metal laminate (Glare) made of 2014-T6 aerospace aluminum alloy sheets adhesively bonded with E-glass fiber based composite prepregs is investigated in the paper. The fabrication procedure of the laminate is explained. Chemical composition, macrostructure and residual stress of aluminum alloy are obtained. Mechanical properties of the laminate viz. tensile, flexural and shear strengths are measured.

Abstract: In this study, the effect of surface treatment of Al with alkaline (pH 10.5 and pH 12.4) and acidic (pH 3.7) electrolyzed water was investigated on bonding strength of solid phase diffusion bonded Al. Aluminum hydroxide and hydroxyl groups were appeared on the surface of Al which was treated with alkaline electrolyzed water of pH 12.4 at 323 K for 2700 s. It was found that such treatment is similar to the one with NaOH aqueous solution at 323 K for 30 s. For bonding strength, shear strength of the bonded Al specimens treated with electrolyzed water of pH 12.4 at 293 K for 3 s and 30 s were higher than that of the untreated specimen.

Abstract: The paper deals with the influence of geosynthetic reinforcement systems on the quality of asphalt bonding layers. A reinforcing element in the form of a fiberglass grid is incorporated into the road structure between two asphalt layers to prevent the formation of cracks and to reduce the tendency of their subsequent propagation throughout the asphalt layers. At the same time, however, they form a potential weak interlayer on which adjacent asphalt layers may slip. The total 90 drilled cores taken from a laboratory-produced two-layer slabs were subjected to the Leutner shear test. The selection of individual specimens took into account both the type of reinforcement element and the amount of applied bituminous emulsion.

Abstract: The objective of this paper is to present a methodology for the measurement of the uncertainty in the calculation result in the shear strength test. Is intended with this work is to gather subsidies to justify the adoption of the measurement of the uncertainty in calculation procedure as a regulatory requirement and part of the report of wood characterization tests. The motivation for submitting this proposal is due to the difficulty in reaching some technical requirements specified by the rules, especially the requirement on "quality assurance testing and calibration results". The proposed methodology consolidates the procedures necessary to obtain the individual measurement uncertainty of the failure stress and the mean result of the uncertainty of failure stress. This methodology meets the requirements of a quality management system. The uncertainty values of the individual results of failure stress were negligible indicating a high-quality equipment and good calibration of them. The uncertainty of the measurement of the mean failure stress was considerable, indicating the importance of their consideration in the safety of wooden structures.