Deflection (engineering)

About: Deflection (engineering) is a research topic. Over the lifetime, 30862 publications have been published within this topic receiving 298849 citations.

Active integration of tool deflection effects in end milling. Part 1. Prediction of milled surfaces

Abstract: Tools deflection that occurs during machining, and especially when flexible tools such as end mills are used, can result in dimensional errors on workpieces. The study presented here is part one of a two-part paper: it deals with the estimation of cutting forces and the prediction of milled surface. The second part will focus on a methodology that allows to optimize the production rate by compensating the deflection and meeting the part tolerance. Cutting force models have been and are still the subject of a lot of research. The model used is based on Kline and Devor's [5]: a polynomial approximation whose coefficients are obtained by least square methodology is used for the calculation of cutting forces. The machined surface (two axis machining) is determined using the contact point methodology and some experimental tests are done to validate the models.

Shear strengthening of reinforced concrete beams with PBO-FRCM composites

Abstract: The work analyses the functioning of reinforced concrete beams which are shear reinforced with FRCM (Fibre Reinforced Cementitious Matrix) composite mesh on mineral mortar. The analysis of previous tests provides an overview on the efficiency of the related FRP (Fibre Reinforced Polymers) system used for strengthening the beams against shearing forces. The information gathered on the functioning of FRCM strengthened concrete elements show that the key factor in this technology is ensuring appropriate carrying capacity of anchoring of the mesh. The tests were carried out on reinforced concrete beams with different design of lateral reinforcement. The beams differed in terms of the angle of inclination of the reinforcement to the longitudinal axis, as well as in terms of the manner of anchoring the mesh at the top and bottom surface of beams. The destruction mechanisms of beams were analysed and described. Value of deflection measured at the maximum load for all of the beams is significantly greater than the allowable value. The distribution of strains is presented as a function of the load, where the phases of operation in relation to shear of FRCM reinforced beams are visible.

Deflections of an infinite plate

Abstract: Problems associated with the thickness of ice sheets on Canadian lakes led the author to investigate mathematically the deflection of a loaded plate resting upon an elastic foundation. Certain simplifying assumptions, which appear to be not unreasonable, permit the solutions obtained to be applied to the strength of a floating ice sheet. Relations for maximum stress and maximum deflections in terms of known functions are derived, both for a concentrated load and a uniform load distributed over a circular area. The resulting expressions should be tested experimentally to determine their domain of validity. Owing to similarity of conditions, these results may also be applied to the design of concrete roadways and airport runways.

On the Accuracy of Timoshenko's Beam Theory

Abstract: The deflection and rotation which appear in Timoshenko's beam theory may be defined either (a) in terms of the deflection and rotation of the centroidal element of a cross-section or (b) in terms of average values over the cross-section. By consideration of an example for which a theoretically exact solution is available it is shown that the Timoshenko equations may be much more accurate if the latter definition is adopted. The example considered is the vibration of a simply-supported beam of narrow rectangular cross-section. The accuracy of the Timoshenko theory depends on the slenderness ratio of the beam, but even when the depth of the beam is equal to the length the Timoshenko theory differs from the exact solution by less than 3.5% provided definition (b) is adopted. Far larger errors occur if definition (a) is used, the most serious error being associated not with shear deformation but with the moment-curvature relation.

Device and method for control of flexible link robot manipulators

Abstract: A method and device for controlling and dampening undesirable vibrational movement within flexible linkage of a robot arm coupled to a movable, controlled joint and attached drive motor. The method includes the steps of providing position displacement and control in accordance with position and velocity feedback input. In addition, elastic deflection arising within the robot arm is detected and a time-dependent deflection signal proportional to the degree of elastic deflection is generated. A control algorithm develops deflection feedback signals for input to the robot arm which are approximately proportional to the deflection signal and its first two time derivatives, each multiplied by a gain whose value is selected to reduce further elastic deflection. This procedure is applied within flexible robot arm structure by incorporating elastic deflection detection components and by converting the detected deflection signal to deflection feedback signals for application to the drive system of the robot arm. Elastic deflections arising upon movement of the flexible arm structure are almost immediately nullified and the robot arm is allowed to reposition itself without interference from such undesirable forces and resultant robot arm movement.