Tool profile stationarity while simulating surface plastic deformation by rolling as a process of flat periodically reproducible deformation

Introduction. Surface plastic deformation is an effective way to improve the operating performance of machine parts. One of the promising approaches to the design of surface hardening technological processes is the technological inheritance mechanics. To calculate the hereditary parameters characterizing the accumulated deformation and damage to the metal, it is possible to simulate spinning as a process of plane fractional deformation, which significantly reduces the time required for modeling the process. However, upon rotation of the plane in which the stress-strain state is considered, the roller profile changes. The aim of the work is to assess the magnitude of the change in the roller profile in the deformation plane during deformation as an important factor ensuring the accuracy of the solution obtained. Research methods. The roll profile in the warp plane is defined by the intersection line of the roll surface and this plane. The paper presents the procedure for calculating the coordinates of the points of intersection lines, which are curves of the fourth order, depending on the geometric dimensions of the roller and the part, as well as the angle of inclination of the deformation plane. Results and discussion. To estimate the value of the roller profile change, the coordinates of the points of the intersection lines of the roller surface and the deformation plane are determined for the rolling modes corresponding to a sufficiently developed plastic deformation, the obtained lines are approximated in the coordinate system associated with the deformation plane, and the relative change in the coordinates of the intersection lines when the plane was rotated are estimated. As a result of the conducted analytical studies, it is found that even with developed plastic deformation, the relative change in the coordinates of the points of intersection lines does not exceed 0.1%. This indicates the possibility of using a stationary roller profile when simulating rolling using the plane fractional deformation model.

La méthode convergence-confinement. Les contributions du Laboratoire de mécanique des solides (LMS)

La méthode convergence-confinement permet de simuler le creusement d’un tunnel avec la mise en place d’un soutènement par un modèle de déformation plane. La connaissance de la convergence du massif au moment où le soutènement devient actif est une démarche essentielle pour l’application de la méthode. Celle-ci nécessite la détermination du profil longitudinal de déplacement (LDP), qui représente le déplacement radial à la paroi du tunnel en fonction de la distance au front. Dans cet article, nous rappelons les contributions importantes de Pierre Habib et de ses collègues du Laboratoire de mécanique des solides (LMS) dans le développement de la méthode, en particulier sur la prise en compte de l’influence de la pose d’un soutènement rigide près du front sur la courbe LDP.

Perumusan Gaya Atraktif Bola Terapung dengan Metode Eksperimen dan Pengolahan Citra Digital

Two floating object interact each other in a certain time when the initial separation distance of them is not greather than the radius. This interaction is caused by asymmetric deformation in the liquid-air boundary plane due to contact with spherical particles. Asymmetric deformation plane of the liquid-air boundary between the two spheres and outside the sphere results an attractive force. This force is experienced by two balls that interact in a certain period of time until they come close to each other and after contact they will bond and difficult to escape. The position of each ball is observed using a video camera with 25 fps specifications and processed using Python and OpenCV and obtained data on the position of the center of mass of the system at any time until both are in contact. From the equation of position to time, the acceleration value of the ball is obtained, so that the magnitude of the attractive force can be known. The attractive force of the object is varied with the density of the object.

Experimental and Numerical Study of Edge Defects When Turning 17vol.% SiCp/2009Al Composites

In this work, a three-dimensional large-deformation thermo-elastic-plastic finite element model for oblique cutting was established to analyze edge defects during the machining of 17vol.% SiCp/2009Al composites. The formation process of edge defects at the workpiece exit during turning was investigated, and the influence of depth of cut, feed rate, and spindle speed on the edge defect sizes at the workpiece exit was explored. The results show that a negative deformation plane began to form as the cutting tool approached the exit end of cut, and the resultant cracks propagated towards the negative shear deformation plane, which led to workpiece edge defects. In addition, the size of edge defects increased with increasing depth of cut and feed rate, while the spindle speed had less influence on the size of edge defects. The numerical results of the effects of cutting parameters on edge defects were also compared to those of the turning experimental data, and were found to be in reasonable agreement.

Strain Induced Precipitation in Model and Conventional Microalloyed Steels during Thermomechanical Processing

The finishing rolling of microalloyed steels was simulated by double-deformation plane strain compression testing of both model and conventional steels microalloyed with Nb. The flow behavior following interpass delay times of 1-100s was related to the deformed microstructure, the deformation substructure and the strain-induced precipitation. Fe-30wt%Ni is clearly a good model alloy for conventional microalloyed steels, as similar results are observed for both materials. In addition, the location of fine strain-induced precipitates in relation to the deformation substructure can be determined directly using transmission electron microscopy.