Matt Khoshdarregi

University of Manitoba | UMN · Department of Mechanical Engineering

Industrial robots used in manufacturing processes such as drilling of aerospace structures undergo many rapid positioning motions during each operation. Such aggressive motions excite the structural modes of the robot and cause inertial vibrations at the end-effector, which may damage the part and violate the tolerance requirements. This article pr...

Inspection of drilled holes in aerospace Carbon Fiber Reinforced Polymers (CFRPs) is crucial to avoid failure of attachments and disintegration of aircraft structures. Vision-based systems can provide an efficient tool for rapid inspection of holes directly on production lines. However, automatic detection of damages in digital images is a challeng...

Chatter stability in machining flexible parts depends directly on the structural dynamics of the workpiece. This paper proposes a novel two-stage framework that combines finite element (FE) and data-driven deep learning techniques to rapidly predict the varying dynamics of workpieces during machining. An automated framework is developed to create a...

Industrial robots have been increasingly adopted in precision manufacturing applications such as aerospace drilling. However, achieving the strict tolerance requirements of the aerospace industry has been a major challenge due to the relatively poor accuracy of robots. One of the major sources of error which has a detrimental effect on the quality...

Due to their greater workspace and lower cost, industrial robots can provide an alternative solution to CNC machine tools for milling of aerospace parts. However, current machining robots fail to meet the required finishing tolerances (0.1 mm) of the aerospace industry. To improve the accuracy of industrial robots during milling, this paper propose...

Haynes 282 is a relatively new γ′- strengthened superalloy used in static and rotating components of jet turbine engines. An understanding of its high strain rate behavior is required to develop constitutive model to predict and optimize its response under dynamic loading applications. Using the direct impact Hopkinson pressure bar, this study inve...

This paper extends the general threading model developed in Part I to the case of thin-walled workpieces. Structural behavior of a cylindrical shell is dominated by the low-damped flexural modes. Due to the circumferential patterns of the shell modes, the cutting forces result in different instantaneous displacements around the circumference of the...

This paper formulates the generalized dynamics and stability of thread turning operations with custom multipoint inserts. The closed-loop chip regeneration mechanism is modeled by evaluating the effect of the current vibrations and the vibration marks left from the previous tooth. Using the developed chip discretization method, the dynamic cutting...

A generalized mechanics model of multi-point thread turning operations is presented. The cross section of the chip is determined from the thread profiles of the current and previous teeth as well as the infeed settings of the tool. The chip is discretized along the cutting edge, and the cutting force coefficients are evaluated for each element cons...

Mechanics of threading with profiled cutting edges

A feedforward trajectory command shaping algorithm is proposed to simultaneously reduce the contouring errors and avoid structural vibrations in five-axis CNC machine tools. Trajectory shaping is used to avoid the excitation of the transient, inertial vibrations but at the expense of distorting the reference path due to added delay. The contouring...

A vibration avoidance and contouring error compensation algorithm for feed drives is presented. The residual vibrations are avoided by applying input shaping filters on the reference axis commands. The input shaping filter avoids the excitation of the structural modes but at the expense of increasing tracking and contouring errors. The tracking err...

Abstract The present machine tools travel at high velocities with large acceleration and jerk, which creates large inertial loads with wide frequency content, resulting in excitation of the natural frequencies of the machine. This thesis presents a command shaping module which avoids structural vibrations and improves contouring accuracy in five-ax...