Papers by Keyword: Torsion

Abstract: The objective of this study is to give an analytical solution for the Saint-Venant torsion of bars having cross section bounded by two hyperbola arcs. The solution of the problem is based on the theory of uniform torsion which was developed by Saint-Venant and Prandtl. The material of the bar is homogeneous, isotropic and linearly elastic.

Abstract: Magnesium alloys have the advantages being lightweight and high recyclability. On the other hands, it is thought that magnesium has the disadvantage of poor plastic workability at room temperature due to its crystal structure. Especially, in pipe materials, winkles occur on the compressed side during bending. We aim to improve the bending workability in magnesium alloy pipe by torsion and back-torsion. In this study, tensile and compressive tests using specimens of pipes processed by torsion and back-torsion showed reduction the difference of yield stress. Microstructural observation of processed pipes revealed reducing crystal grain size and forming deformation twinning. Vickers hardness tests shows increasing hardness by torsion and back-torsion. Moreover, bending tests showed decreasing flatting ratio by torsion and back-torsion. These results demonstrated that torsion and back-torsion have effect of improvement in bending workability for magnesium alloy pipes.

Abstract: Instability is one of the factors causing damage and injury that results in permanent disability. To increase the stable load-carrying capacity, a simplified and efficient computational method for determining the first critical load is necessary for the structure's structural design, application and safety. This study aims to determine the characteristics of the critical bending moment M_bcr and the critical torsion moment M_Tcr due to geometric size variations in the square, diamond, and circle cross-sectional hollow pipes so that consideration of the selection of hollow pipe size and cross-sectional shape is obtained under pure bending and pure torsion to minimize the occurrence of instability of the structure. The geometric size variation is carried out by changing the value of a/t in the quadrilateral pipe, the value of D/t in the circular pipe, and the length of the pipe L in each cross-sectional shape. This research was conducted using Finite Element Analysis-based software with linear and nonlinear buckling analyses. The moment load is given at the centre point of the model end, and the boundary conditions are set to see the deformation on the mid-span section of the pipe. The results showed that M_bcr and M_Tcr were inversely proportional to the values of a/t, D/t, and . The largest value of M_bcr belongs to the circular pipe. The value of M_bcr in the diamond pipe is greater than the square pipe but getting closer to the same as the value of L increases the M_Tcr value of both cross-sections is the same. The M_Tcr curve in the cross-section of the circle has a higher degree of steepness than the square and diamond cross-section. At the same value, the more the value of a/t and D/t increases thickness change has more compared to the circular pipe. At the same L, the greater the value of a/t and D/t, the difference in the M_bcr between the cross-section of the circle and the quadrilateral is smaller, but the difference in M_Tcr tends to be the same. At the same value of a/t and D/t, the oval deformation value and angle of twist will get bigger, but the M_bcr and M_Tcr values are getting smaller and will be constant at a given pipe length.

Abstract: ST 41 steel is a low carbon steel which can be used for propeller shafts because it is categorized as a carbon steel permitted by BKI with a tensile strength requirement of 400 to 800 N/mm². The propeller shaft deteriorates due to its surface frequently rubbing against the bearings. Carburizing is a technique used to increase the surface hardness by heating the specimen in a closed container containing mixture of carbon and a catalyst. The main objective of the subsequent quenching and tempering processes is to increase toughness and ductility while eliminating residual stresses. The achieved results are based on tests conducted on ST 41 steel with a measured carbon layer thickness of 229.12 μm, namely coal carbon media. Based on the results of wear tests, coal carbon media possesses a minimum value of 6.38287E-05 mm²/kg. In torsional testing, the maximum shear stress value for carbon media made from coconut shell charcoal is 429.79 MPa. When measuring hardness, coal carbon media has the highest value, which is 340.918 VHN. And metallographic testing shows that pearlite is the main phase in coal carbon media. The media with the most carbon is coal carbon, which 0.729% on the surface of the steel. Keywords: St 41 Steel, Carburizing, Wear, Hardness, Torsion, Chemical Composition, Micrograph.

Abstract: We report on an analytical model for damage description in adhesive butt joints. In themodel, the thin adhesive layer is replaced by a damaging bonding interface. The mechanical behaviorof the interface is described by a nonlinear and rate­dependent imperfect contact law. The law takesinto account both stress and displacement jumps, and it can describe both soft and hard adhesive layers.Unlike classic cohesive zone models, phenomenological in nature, the proposed contact law explicitlyaccounts for material and damage properties of the adhesive layer. A first comparison with literaturedata of adhesive butt joints loaded in torsion indicates that the model can successfully reproduce theirexperimental stress­strain response.

Abstract: In this study, an experimental investigation was done to study the behaviour of Normal Strength Concrete (NSC) and High Strength Concrete (HSC) Plain beams under torsion with the concrete mix of M40 and M100. No mineral admixtures are used to obtain the required strength of concrete. Eight NSC beams and eight HSC beams whose width was varying with 75 mm, 100 mm, and 150 mm; depth varying as 75 mm, 100 mm, 150 mm and 200 mm; and span of the beams varying 600 mm, 800 mm and 1200 mm were casted and cured to stud the effect of torsion. The principle aim of this study was to understand the torsional behaviour of the NSC and HSC beams for rotation, cracking, size effect and torsional strength. A standard torsional loading method was used for conducting the testing of beams. The results obtained were compared with different theories and code equations. It was observed that the torsional strength of the beam increases with the increase in strength of concrete. HSC beams have higher torsional strength than the NSC beams which has the same amount of reinforcement.

Abstract: The present paper deals with an analytical study of the time-dependent delamination in a multilayered inhomogeneous cantilever beam with considering of the loading history. The multilayered beam exhibits creep behaviour that is treated by using a non-linear stress-strain-time relationship. The material properties are continuously distributed along the thickness and length of the layers. The external loading is applied in steps in order to describe the loading history. The analysis reveals that during each step of the loading, the strain energy release rate increases with time. The influences of crack length and location on the time-dependent strain energy release rate are also investigated.

Abstract: The present paper analyzes the influence of creep on longitudinal fracture in continuously inhomogeneous rod of circular cross-section loaded in torsion and bending. The rod exhibits continuous material inhomogeneity in both radial and longitudinal directions. The creep is described by using non-linear time-dependent relations between the principle stresses and strains. A time-dependent solution to the strain energy release rate is derived by analyzing the complementary strain energy. The time-dependent strain energy release rate is found also by considering the energy balance for verification. The solutions are applied to perform a parametric study of the strain energy release rate under creep.

Abstract: Cold drawn wires were produced by drawing the pearlitic wire rod (5.5 mm diameter). Cold drawing involved multiple stages to a final drawing strain of ≈ 2.5. The cold drawing alters the pearlite morphology. During the wire drawing, the change in morphology is location dependent. This will create the gradient in stain and strain mode between the surface and the center. This led to have a strain partition among ferrite and cementite phases. The strain partitioning plays a major role in the final tensile and torsional performance of the cod drawn wire. The present work dealt with the experimental and their numerical simulations of stress gradients and the role of pearlite morphology on tensile and torsional properties of the pearlitic steel wire.

Abstract: The numerical investigations were carried out to study the behavior of reinforced concrete beams strengthened by CFRP under different loading conditions (pure bending and combined bending and torsion). The numerical work included analysis of eight experimentally tested beams of rectangular cross-section dimensions of (160×240) mm and (2600) mm length keeping the area of the ordinary reinforcement constant for all beams. The following parameters were taken into consideration, twisting to bending moment ratio (T/M) and CFRP strengthening arrangement. The analyzed beams are divided into four groups. Each group consists of two beams; the first beam is without CFRP strengthening, the other beam is strengthened with CFRP. Each beam is loaded to a different loading conditions (pure bending, T/M=0.5, T/M=1.0, T/M=2.0). The CFRP sheets were attached externally to the beam. Analysis results were analyzed based on influence of CFRP on ultimate load and vertical mid-span deflection. According to the numerical study, it was found that all strengthening arrangements of CFRP sheets exhibited a significant increase in ultimate strength. The three-dimensional (3D) finite element model (FEM) utilized in present work is capable to simulate the behavior of externally strengthened reinforced concrete beams by CFRP. Full bond connections (no slip) are assumed between the CFRP sheets and surface of concrete. The comparison between the numerical and the experimental results declared the validity of the numerical analysis where the range of the (P_exp./P_ANSYS) ratio in ultimate load was from 0.847 to 1.157. The general behavior of the (FEM) shows good agreement with the test results from the experimentally tested beams.