in the present paper, the deformation zone of the ecae (equal channel angular extrusion) process was investigated using the upper bound theorem. for this purpose, the shape of the streamlines in the deformation zone was assumed to be cubic bezier curves. then, the force required for the ecae process was optimized with regard to the parameters defining the shape of streamlines by the upper bound...

In this study, an analytical slip-line approach is utilized to investigate the friction factor at the tool-chip interface and dead metal zone phenomenon in orthogonal cutting with chamfered tools. Analytical thermal modeling of chamfered tools is also formulated and integrated into the model. Orthogonal cutting of AISI 4340 steel is performed. Measured forces are utilized in identifying the fri...

This paper proposes an adaptive approximation-based controller for uncertain strict-feedback nonlinear systems with unknown dead-zone nonlinearity. Dead-zone constraint is represented as a combination of a linear system with a disturbance-like term. This work invokes neural networks (NNs) as a linear-in-parameter approximator to model uncertain nonlinear functions that appear in virtual and act...

A study has been made of the deformation field in plane-strain indentation of metals with a flat punch. Deformation field parameters such as velocity and strain rate have been measured using the technique of particle image velocimetry. For this purpose, images of the indentation region were recorded in situ during the deformation process, and motion of ‘asperities’ specially introduced onto a s...

High speed cutting is advantageous due to the reduced forces and power, increased energy savings, and overall improved productivity for discrete-part metal manufacturing. However, tool edge geometry and combined cutting conditions highly affects the performance of high speed cutting. In this study, mechanics of cutting with curvilinear (round and oval-like) edge preparation tools in the presenc...

microbial cells have been successfully used as biosorbents to remove heavy metals from wastewater. in some cases, dead cells appear to offer more advantages than living cells in the removal and recovery of heavy metal ions from industrial wastewater. maintaining higher biosorption capability and understanding the biosorption properties of dead cells are the keys to heavy metal removal and recov...

An adaptive tracking control problem is investigated for a class of nonlinear system with non-symmetric actuator dead-zone fault. Based on adaptive compensation algorithm, a new adaptive controller specially designed is employed without constructing the dead-zone inverse. This paper studies the dead-zone fault model is more universal. The restrictions that the dead-zone slopes and the boundarie...

This paper presents an approach for dead zone compensation in pneumatic position servo systems. The dead zone is an inherent nonlinearity in pneumatic servovalves, where for a range of input control values, the valve gives no output flow. Although pneumatic actuators are very common in industry, they have limitations in servo pneumatic applications that are caused by typical non-linearities of ...