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Torsion
Published in B. Raghu Kumar, Strength of Materials, 2022
Torsion refers to twisting of a structural member when it is loaded by couples /moments that produce rotation about its longitudinal axis. If a pair of forces acting tangentially so that longitudinal rotation occurs, the torque can be calculated as force multiply with the perpendicular distance between the forces.
Mechanical Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
The other damping mechanisms involve clamping loss and internal friction (the motion-resisting force between the surfaces of particles making up a substance) within the microcantilever. Clamping loss, occurring at the joint, grip, or support, has a negligible contribution to the total dissipation in the longer microcantilever, possessing high length-to-width and width-to-thickness ratios. However, the ultimate minimization-of-clamping loss is achieved in oscillators with double-paddle or butterfly geometries, instead of single-clamped cantilevers or double-clamped bridges. Hence, scientists delving into fundamental studies of intrinsic friction effects in MEMS frequently perform resonance measurements in double-paddle resonators. Q-factors as high as 105 have been reported for torsional butterfly-shaped resonators fabricated from single-crystal silicon. Torsion refers to deformation caused when one end of an object is twisted in one direction and the other end is held motionless or twisted in the opposite direction.
Design of Composite Structures
Published in Manoj Kumar Buragohain, Composite Structures, 2017
From strength and stiffness points of view, a torsion member is designed so as to keep the shear stresses and angle of twist within respective allowables. Thin tubular members can undergo torsional buckling and in such a case, stability becomes the design driver.
Topology optimization for disc structures with buckling and displacement constraints
Published in Engineering Optimization, 2023
Weiwei Wang, Hongling Ye, Zonghan Li, Yunkang Sui
Torsional discs are widely used in mechanical engineering to transmit motion or loads by making use of the in-plane torsional stiffness. They are designed from the aspects of thickness and in-plane material layout. The displacement at any point is inversely proportional to the thickness of a disc plate, and the relationship between the critical buckling load and the thickness is cubic. The stability decreases more rapidly than the ability to resist distortion when the disc plate is thinned. Thus, it is necessary to find an in-plane material layout with a good stability performance. Therefore, a structural optimization framework with a comprehensive consideration of both stiffness and stability performance is urgently needed to solve the design problem of torsional disc structures. This would improve the robustness of disc designs and be valuable in avoiding repeated rectification and reducing the design cycle.
Optimization of torsion and wear characteristics on reinforced steel wire rope
Published in Mechanics Based Design of Structures and Machines, 2022
Saravana Kumar Palanisamy, Manonmani Krishnaswamy
The three objectives such as wear, torsion, and fatigue are considered in this work, wear is the slow removal, damage, or deformation of the material. In material science, the cause of wear can be mechanical or chemical (e.g., corrosion). The rate of wear is affected by factors such as temperature, type of loading, type of motion, and lubrication. Torsion is the twisting of an object due to an applied torque. Fatigue is the weakening of a material that is produced by progressive cyclic loading and which results in localized structural damage and the growth of cracks. The fitness functions are described below
Experimental Investigation of the Seismic Performance of Rectangular Reinforced Concrete Columns Subjected to Combined Flexure-torsion Cyclic Loading
Published in Journal of Earthquake Engineering, 2020
Nahid Attarchian, Nader K. A. Attari, Zakariya Waezi
In practice, pure torsion rarely happens in the structural members; torsion usually occurs in combination with shear, axial, and flexural moment demands. However, estimating the behavior of members subjected to pure torsion is necessary for understanding the behavior of structural members subjected to combined loadings. In order to guarantee the acceptable behavior of the specimens under pure torsion, the transversal reinforcement ratio assigned to be 1.9% for all specimens (Table 1). For the ST specimen subjected to pure torsion, the torsional stiffness degraded at a rotation about 0.004 rad for clockwise rotation and 0.0035 for counterclockwise rotation (Fig. 9). The points (A and B) corresponding to the initiation of the torsional stiffness degradation are shown with red squares in Fig. 9. The results for both clockwise and counterclockwise loading cycles are presented in Table 3. The torsional moment strength of the specimen corresponding to the initiation of the torsional stiffness degradation, which is described as the cracking torsion in the design codes, was about and for the clockwise and counterclockwise loading, respectively (Table 3). According to ACI 318 (ACI Committee 2014) the cracking torsion of the column is about , which is in good agreement with those obtained from experimental results. It can be seen that the proposed value of cracking torsion by ACI 318 corresponds to the initiation of the torsional stiffness degradation. It should be noted that in pure torsion test, the first loading cycle was clockwise and the second loading cycle was counterclockwise. Under pure torsional loading, diagonal cracks started developing near mid-height of the column and propagated and increased by increasing the applied torsion. After point A and B, the hysteresis curve is approximately linear up to the peak torsional moment strength. As it is shown in Fig. 9, The peak clockwise torsional moment strength and the corresponding rotation (point C) is about 127kN.m and 0.063 rad, respectively (Table 3) and the peak counterclockwise torsional moment strength and the corresponding rotation (point D) were resulted to be and 0.053 rad, respectively (Table 3). The test was stopped when the resisting torsion was dropped up to 80% of the peak torsional moment strength and the maximum rotation capacity of the section was 0.12 rad.