Purpose The purpose of this paper is to investigate the effect of graphene platelets (GPLs) on the low-speed contact between a mass and surface of a multi-layer polymer beam. Design/methodology/approach This problem is primarily organized by first-order shear deformation beam theory and nonlinear Hertz rule. GPLs are distributed along the beam thickness direction. The Halpin–Tsai micromechanics model is applied for computing the effective Young’s modulus of the GPLs/polymer composites. In the formulation process, the principle of conservation of energy is first used and the histories of results are extracted using the separation of variables and Runge–Kutta method. Findings In comparing the responses with the available data, a good agreement is observed. The effects of the weight fraction and distribution pattern on the impact response of polymer beam reinforced with GPLs are studied. Results show that contact force is increased, contact time and beam recess are decreased with increasing of weight fraction of GPLs. Also, among the different distribution patterns, the contact force depended on value of GPLs at the point of contact. Originality/value The effects of GPLs addition on the multi-layer polymer beam has a novelty in impact problems.

In the first part of this paper, a new type of profiled rotor that rotates a working machine is presented. The machine is able to function either clean or with a suspension fluid. The aim of this work is to study the strength needed to overcome the viscous friction of two pairs of surfaces: between the case and the top of the piston and between the walls of the case and the rotor side surface. This paper includes a graphical presentation of the power consumption in both cases. The final part of this paper highlights the advantages of rotating machines with two profiled rotors. A reference list, which highlights the ongoing research into rotating machines with profiled rotors, concludes this paper.

The process of laser cutting by (Nozzle C 20E) can detect the roughness of the surface from the upper side, while laser cutting by (Nozzle C30E) have less roughness detection according to the ability of constant speed with different metal thickness. The width of the Kerf and surface roughness are the most factors which needs for focusing during cutting process for various plate cutting operation by CNC machine. Such machines require oxygen and propane or acetylene gases with proper pressure controls. For the gas cutting machine, the volume of oxygen gas used is more than that of propane gas. The oxygen gas is used for heating and cutting the plates. It is necessary to supply the proper amount and quality of gas to the machine to obtain a good cutting quality surfces. However; the pressure of oxygen gas depends upon the thickness of cutting plates. Stainless steel is the most important metals in the industrial and manufacturing process, so the cutting conditions are very important. Its concluded from our result, that the characteristics of the main selecting factors which effects the laser machine performance such as, the focal lens nozzle height (0.6 to 1.0mm) and the ability and speed of cutting should be fixed and not changing.

The study of cracks behaviour in a composite plate is of significant importance in the dynamics of the Mechanical parts in order to avoid design failures due to resonance or high amplitude vibrations. In this paper, a square glass-epoxy composite plate is adopted. The plate has four layers with symmetric and asymmetric lamination. Assuming the cracks are profound as defects. The results were obtained by using a numerical solution of mechanical APDL from ANSYS. It has been found for different boundary conditions that the rank of natural frequencies is decreased by increasing the crack ratio due to the reduction of the plate’s stiffness, whereas the crack direction has no mentioned effect for a small angle of rotation. The accuracy of results is verified by comparing a single case of the current work with other previous investigations. Evaluate the influence of the crack length ratio, angle of the crack rotation, boundary conditions and lamination angles on the natural frequencies of the square composite plate with glass-epoxy materials.