Material flow

About: Material flow is a research topic. Over the lifetime, 3050 publications have been published within this topic receiving 36844 citations. The topic is also known as: material stream.

Investigation on the material flow and deformation behavior during ultrasonic-assisted incremental forming of straight grooves

Abstract: The introduction of ultrasonic vibration is proved to be beneficial for the reduced force and improved formability for sheet forming processes. However, the vibration-induced material behavior is still not satisfactorily explained. The objective of this work is to investigate the effect of the ultrasonic vibration on the material flow characteristics and the plastic deformation mechanism during the incremental sheet forming of the straight groove. Both analytical and finite element models are established to explore the impacts of ultrasonic amplitude, frequency, step-down size and feed rate on material flow characteristics. It was found that the material flow area was dramatically increased after applying the ultrasonic vibration, and the influence of ultrasonic amplitude on material flow area is greater than that of frequency, which is similar to the effect of acoustic softening. In addition, the separation effect under different amplitudes and frequencies was analyzed through finite element modeling to partly explain the reduction of forming forces. The duty cycle was decreased as the amplitude increases as well as the frequency. Furthermore, the material flow behavior and the force reduction rate for different tool paths are explored. Finally, experiments were performed which further verified the reliability of the analytical and FE models. These findings provide a theoretical basis for further investigation of the mechanisms of ultrasonic-assisted incremental sheet forming process.

Textured surfaces for deep drawing tools by rolling

Abstract: In this paper, macroscopic textured tool surfaces manufactured by rolling are investigated. Focus is on selective adjustment of friction by local texturing of tool areas to influence the material flow during deep drawing operations. Flat strip drawing tests were performed using friction elements with open textures. The texturing influences the friction conditions and affects the material properties of the stripes. The use of these surfaces results in a significant increase in friction, which allows an additional control of the material flow during sheet drawing operations. The main mechanisms for increased drawing forces are elastic deformation near the area of the texture and local plastic deformation on the sheet surface. Using strips made of mild steel, the texturing leads to an increased roughness of the sheet metal surface and, in the case of high surface pressure, to plastic deformations of the strips. Compared to conventional measures like draw beads, rolled-textured surfaces allow to retard the material flow during sheet drawing operation without excessive strain hardening in the sheet material.

Robust boundary flow in chiral active fluid.

Abstract: We perform experiments on an active chiral fluid system of self-spinning rotors in a confining boundary. Along the boundary, actively rotating rotors collectively drive a unidirectional material flow. We systematically vary rotor density and boundary shape; boundary flow robustly emerges under all conditions. Flow strength initially increases then decreases with rotor density (quantified by area fraction ϕ); peak strength appears around a density ϕ=0.65. Boundary curvature plays an important role: flow near a concave boundary is stronger than that near a flat or convex boundary in the same confinements. Our experimental results in all cases can be reproduced by a continuum theory with single free fitting parameter, which describes the frictional property of the boundary. Our results support the idea that boundary flow in active chiral fluid is topologically protected; such robust flow can be used to develop materials with novel functions.

Flow control system for spray applications

Abstract: A spray control system for applying a coating composition to an object. The control system includes an applicator, flow control valve, flow meter, and an electronic controller connected to the valve and flow meter. The controller regulates the flow of coating composition to maintain it at a user-specified setpoint. The controller includes a learn mode in which it learns the proper valve setting for a particular setpoint and stores a valve control signal that is later used at the start of a spray application to initially set the valve at the proper position. Then, once the flow of material begins, the controller uses either incremental or proportional control, or both, to maintain the flow at the specified setpoint. When learning a setpoint, the controller also stores the current values of a number of user-specified process parameters, such as ambient air temperature and the coating composition source pressure. These stored parameter values are then monitored during the spray application and an alarm notification is provided if they drift outside of a window about their stored values. The controller is configured to adapt to changing environmental and operational conditions by re-learning the proper valve setting for a particular setpoint each time the flow sufficiently stabilizes at the setpoint. Circuitry is also disclosed for use in connection with the flow meter to quickly determine the flow rate at the commencement of material flow and to provide fast updating of a conventional digital readout of flow rate.