Papers by Keyword: Shearing

Abstract: Studying of the strength characteristics of polymer composite materials, which are used in the structures for various applications, is an important subject for research. Here one of the major issues is the development of fastening techniques to maximize the strength characteristics of composite fibers. Based on the modification of the available test methods, a set of specimens and devices has been developed to determine the shearing (cut) strength from the fastener hole to the edge of the composite part. For this purpose, we used the modified specimen sequentially shearing along the contour after each test cycle in order to find the required parameter depending on the distance from the fastener to the part edge. According to the result of experimental studies, possible types of shearing test and shear test failures were identified. It is demonstrated that shearing strength and shear strength in the specimen plane are different characteristics with no correlation between them. It is found that a shearing in the classic sense is observed only for high-anisotropy structures when they are loaded in the more rigid direction, whereas the complex modes of failure occur for the heavily reinforced composites used. For example, during testing a pure shearing was observed in 0° planes in the specimens with the package structure of [0^°_0.7; ±45^°_0.2; 90^°_0.1], while it was observed both for the holes drilled in 0° and 22.5° directions in the specimen with the structure of [0^°_0.8; ±45^°_0.2]. We obtained the quadratic engineering dependence to predict shearing strength of the heavily reinforced basic composite. Based on processing of the experimental results, a recommendation has been made on the need for constant experimental support of the design process, which can be implemented by the proposed specimen and testing device.

Abstract: This research was carried out to study punch/die shear cutting of betel palm sheath. In a shear cutting experiment, shearing process parameters i.e., the moisture content of the palm sheath and the punch/die clearance were varied and investigated. Experimental results showed that both of the process parameters played an important role on the surface cracking of the palm sheath. In order to discuss the cutting characteristics of the palm sheath, a finite element method (FEM) analysis of the shear cutting was conducted. Based on simulation results with the surface cracking observed in the experiment, it was confirmed that the position of the peak maximum principal stress on the palm sheath surface varied with the punch/die clearance. Also, the position of the surface cracking was relevant to the position of the peak maximum principal stress.

Abstract: In this study, the effect of die edge radius on crack initiation was discussed in finish blanking. Experiments were carried out using die with rounded cutting edge. As a result, it was confirmed that crack initiation near the punch edge occurred earlier than that near the die edge. It was also confirmed that the burnished surface increased with an increase in the die edge radius. Finite element method was carried out from the initial stage of shearing and until the punch penetration depth was achieved just before the occurrence of the cracks to investigate the distribution of the mean stress. As a result, it was confirmed that the punch stroke, where the mean stress began to increase rapidly to a positive value, increased with an increase in the die edge radius, and the punch stroke at which the mean stress increased rapidly also increased.

Abstract: This study investigated the effects of the die clearance on the shearing and shaving processes of the stainless steel (SUS316LVM) wire at micro scale. A die set was developed and installed on a precession press equipped with a load cell and a displacement sensor to conduct experiments. By using different punches in the same die set, the specimens prepared from 316LVM stainless steel wires with 0.5 mm diameter were first sheared and then shaved. Experimental results show that the burnished area of the sheared edge increases with the reduction of the clearance between the punch and die in the shearing process. The clearance also significantly affects the load curves. Moreover, the shaving process does increase the burnished area on the shaved edge of the specimen. By an appropriate feed in the shaving process, it is possible to trim the extra material from the sheared edge that results in a nearly complete burnished surface on the shaved edge of the stainless steel wire. This research provides a basis for understanding of the die clearance effect on the shearing and shaving processes at micro scale.

Abstract: The usage of AAC (Autoclaved Aerated Concrete) blocks for the construction of new masonry structures, particularly low-rise residential buildings, has become very popular in Poland. It provides an uncomplicated erecting method, which is characterized by thin bed joints and unfilled head joins, but at the same time, makes these walls very sensitive to any internal tensile stresses, causing damage with varying intensity. To avoid premature cracking, leading to a brittle failure of existing walls, an external strengthening can be an acceptable and effective solution. Taking into account that AAC units are a natural material, the application of a FRCM system (instead of FRP) is more suitable here. This system uses a mineral-based matrix that provides congenial compatibility with a masonry substrate.This study presents an analysis of the influence of superficial strengthening on the behaviour and deformability of masonry walls made of AAC blocks. A typical glass mesh (most often used in thin external plastering) and mineral mortar dedicated to renovation works are used as strengthening materials. The specimens are strengthened unilaterally (two types) or bilaterally and are subjected to diagonal compression according to the RILEM 76-LUM standard. The consecutive work stages, shear strains and modes of failure are described and discussed.

Abstract: The mechanism of galling generation is studied with finish blanking using TiCN coated punch. A high-tensile-strength-steel plate with a thickness of 6mm is used in the present paper. The edge shapes of punch are two types, a punch with 1.0 mm chamfered edge (C1.0 punch) and a punch with right angle edge (RA punch). The clearance is kept to 0.5%t, and lubrication is not used in this experiment. Galling is observed at the first shearing operation except for RA punch, and galling can’t be found clearly even when the shearing number reaches 20 in the case of the RA punch. In order to clarify these differences of RA punch and C1.0 punch, the oxygen on burnished depth is observed by electron probe micro analyzer (EPMA). The oxygen is not detected on the burnished depth sheared by RA punch. On the other hand, the oxygen is detected on the burnished depth sheared by C1.0 punch. In the case of C1.0 punch, the oxide scale on the plate surface flow into the burnished depth because of the low surface expansion ratio of the burnish depth. Thermochemical simulation is carried out using a commercial code MALT and gem which solves chemical equilibrium problems by minimizing the gibbs energy of the system. TiCN reacts with oxide scale to form Fe and Fe₄N. As result of analyzing galling part of C1.0 punch from the cross section direction, Fe, Fe₄N, FeTiO₃ and Fe₂TiO₄ are detected and those detected elements coincides well with the Thermochemical simulation.

Abstract: This research work was carried out aiming to investigate the cutting characteristics of a soft metallic sheet subjected to the wedge blade indentation. The indentation of a lead alloy worksheet was conducted, experimentally using a center bevel blade in order to reveal the experimental background of the indentation. In addition, to investigate the effects of the blade tip geometry, the bevel angle of the wedge blade, on the cutting characteristics of the worksheet, the finite element method (FEM) analysis was conducted. By varying the bevel angle, the critical levels of stresses for the necking of the worksheet were detected. Also, it was found that the bevel angle affected the cutting load resistance, the necking of the worksheet and the final feature of the wedged edge.

Abstract: Currently, the shaped parts combined with straight, concave, and convex portions are increasingly fabricated. To produce the straight portion, the shearing theory is usually applied. As well as, to produce the concave and convex portions, the punching and blanking theories are usually applied. However, with the same die-cutting process parameters, the comparison of cut surface features of straight, concave, and convex portions has not been investigated yet. Therefore, in the present research, the comparison of the cut surface features in various die-cutting processes, including shearing, blanking, and punching processes are investigated. The finite element method (FEM) was used as a tool to investigate these cut surface features. The cut surface features were investigated and clearly identified via the changes of the stress distribution analyses. The results elucidated that with the same die-cutting process parameters, the different cut surface features were obtained. Specifically, the crack formations were easily generated in the case of blanking process, following by the shearing and punching processes, respectively. Therefore, the smooth cut surface was smallest in the case of blanking process, following by the shearing and punching processes, respectively. The laboratory experiments were carried out to verify the accuracy of the FEM simulation results. Based on the cut surface features, the FEM simulation results showed good agreement with the experimental results in terms of the cut surface features. Therefore, to design the die-cutting process parameters to meet the product requirements of complicated shapes, the understanding on these working process parameters being upon the shaped parts is necessarily.

Abstract: Shearing is the cutting of a sheet material with a punch and a die. The cut surface obtained by shearing is composed of rollover, a sheared surface, a fracture surface and burr. It has been reported that rollover is formed by the insufficiency of material and material flow in the lateral direction. However, the rollover in the sheet material on the die and that in the sheet material under the punch have not been evaluated individually in previous studies. In this report, the relationship between the material flow and the formation of rollover in the sheet material on the die is discussed on the basis of experimental results obtained by image processing. The relationship between the material flow and the formation of rollover in the sheet material under the punch also is discussed. Double-sided shearing with a counter punch was carried out. The deformation of the sheet material was observed through reinforced glass using a high-speed CCD camera. The image processing was carried out to investigate the material flow. The results were as follows. When the clearance is small, the material flow in the clearance is toward the sheet material on the die. When the clearance is large, the material flow in the clearance is toward the sheet material under the punch. The area of rollover in the sheet material on the die is equal to the sum of the amount of material flow in the clearance and that in the lateral direction. On the other hand, the area of rollover in the sheet material under the punch is equal to the sum of the amount of material flow in the lateral direction under the punch, that in the clearance and the insufficiency of material. These findings are useful for considering the relationship between the material flow and the formation of rollover in the case that the rollover in the sheet material on the die and that in the sheet material under the punch are evaluated individually.

Abstract: Livestock provides the motive power sustaining the life of local population and small scale industries in Pakistan. Obtaining meat and milk from sheep for the human consumption and by-products such as skins, wool, hair for local use and plays key role for the economical stability and growth of the country. There is massive amount of wool sheared by local peoples in Baluchistan but due to lack of education and technical knowledge regarding the wool shearing have remained as major issue. Shearing is made on annual or biannually, but even needs certain expertise and professionalism in the sorting of wool. The textile industry of country has greater challenge for last few decades. Government needs to upgrade vocational and technical education as well as the new equipments and machinery for wool processing in the region. Several initiatives are also being carried by small and medium enterprise for the economical uplift of region particularly and country in general. Mostly obtained wool from various regions remained as major issue for its sorting and processing for finished textiles.