Rotary ultrasonic slot machining (RUSM) of ceramic matrix composites is explored. A comparison is made between RUSM and conventional diamond grinding by studying the effects of material removal rate ...(MRR) on process forces, tool wear and surface roughness. It was shown that RUSM leads to a significant decrease in process cutting forces and tool wear in comparison to the conventional machining process. Furthermore, the influences of diamond tool characteristics on surface roughness and tool wear are also ascertained.
An analytical model of rotary ultrasonic milling Bertsche, Erich; Ehmann, Kornel; Malukhin, Kostyantyn
International journal of advanced manufacturing technology,
04/2013, Letnik:
65, Številka:
9-12
Journal Article
Recenzirano
Rotary ultrasonic machining is currently being used as a manufacturing method for advanced ceramic materials, but its complexity has hindered its acceptance in industry. For this technology to gain ...wider acceptance, it must first be scientifically better understood. The majority of published rotary ultrasonic machining (RUM) papers studied the effect of RUM process parameters on machining performance and removal mechanisms for drilling of circular holes. In industries such as aerospace, the production of advanced turbine components requires machining of complex 3D features using milling strategies. The objective of this paper will be to present a new physical model based on rotary ultrasonic milling which will help provide a better scientific understanding of the process. This will be accomplished by first modeling the macro kinematics between the tool and material followed by the modeling of micro kinematics between the individual diamond grains and the material. In addition, a force model for predicting machining process forces will also be introduced and validated based on a set of experiments. The physical models will help determine the relationships between input parameters, cutting parameters, and process output parameters for rotary ultrasonic milling.
Model of a NiTi shape memory alloy actuator Malukhin, Kostyantyn; Ehmann, Kornel
Journal of intelligent material systems and structures,
03/2015, Letnik:
26, Številka:
4
Journal Article
Recenzirano
A model of motion of an agonistic–antagonistic shape memory alloy actuator is developed in this article. The model shows that the dynamics of the actuator can be well described by a nonlinear motion ...model of human muscle with nonlinear damping. To complete the model, a method for the determination of the damping properties of the actuator system is suggested. To this end, an analytical expression for the damping coefficient of the system was developed. The experimental verification of the proposed model of motion was conducted through a comparison of the experimentally measured and numerically simulated step responses. The simulated step responses were in close agreement with their experimentally measured counterparts on the shape memory alloy actuator prototype.
A theoretical framework, united by a “system effect” is formulated to model the cutting/haptic force evolution at the cutting edge of a surgical cutting instrument during its penetration into soft ...biological tissue in minimally invasive surgery. Other cutting process responses, including tissue fracture force, friction force, and damping, are predicted by the model as well. The model is based on a velocity-controlled formulation of the corresponding equations of motion, derived for a surgical cutting instrument and tissue based on Kirchhoff's fundamental energy conservation law. It provides nearly zero residues (absolute errors) in the equations of motion balances. In addition, concurrent closing relationships for the fracture force, friction coefficient, friction force, process damping, strain rate function (a constitutive tissue model), and their implementation within the proposed theoretical framework are established. The advantage of the method is its ability to make precise real-time predictions of the aperiodic fluctuating evolutions of the cutting forces and the other process responses. It allows for the robust modeling of the interactions between a medical instrument and a nonlinear viscoelastic tissue under any physically feasible working conditions. The cutting process model was partially qualitatively verified through numerical simulations and by comparing the computed cutting forces with experimentally measured values during robotic uniaxial biopsy needle constant velocity insertion into artificial gel tissue, obtained from previous experimental research. The comparison has shown a qualitatively similar adequate trend in the evolution of the experimentally measured and numerically predicted cutting forces during insertion of the needle.
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A model, describing the kinetics of the temperature-induced austenite phase transformation processes in shape memory alloys (SMAs) is presented. The model is formulated for a general stress and ...temperature state in the solid body and allows the computation of the austenite phase fraction evolution in it, that is, the dependence of the amount of the austenite phase fraction on the values of the temperature and stress. It is shown that the predicted amount of the austenite phase fraction is not dependent on the control volume discretization. The model does not take into account microstructural changes in the material and the existence of different phases in the material (R-phase, twinned martensite). The experimental verification of the model was conducted using SMA nitinol wire that was prestrained (detwinned martensite state) and subjected to a heat load. It was shown that the austenite phase fraction predicted by the model agrees very well with the tabulated (reference) and experimental data.
A shape memory alloy based tool clamping device Malukhin, Kostyantyn; Sung, Hankyu; Ehmann, Kornel
Journal of materials processing technology,
04/2012, Letnik:
212, Številka:
4
Journal Article
Recenzirano
► We introduce a new concept of effective micro-tool clamping. ► The suggested clamping concept is based on SME property of SMA NiTi alloys. ► We propose two alternative clamping designs and their ...experimental prototypes. ► The suggested clamping mechanisms tested to be effective in micro-tool clamping.
The traditional collet-chuck mechanism for tool clamping is a significant source of errors in spindles due to stack-up tolerances. This, in turn, adversely affects the tool's error motions particularly in demanding micro-cutting operations performed with ultra-high-speed miniaturized spindles. Hence, novel thought for miniature tool clamping is needed to minimize tool run-out and error motions in order to meet the necessary cutting speeds and accuracy requirements. In this paper a couple of Shape Memory Alloy (SMA) based solutions for the clamping of miniature tools will be explored. For clamp actuation the so-called Two-Way Shape Memory Effect (TWSME) property of NiTi SMAs will be exploited. The basic principles, design requirements, analysis and physical realization of these devices will be discussed. It will be shown through experimental verification tests that clamping forces in excess of tens of Newtons are possible, confirming thus the feasibility of the proposed solutions.
Hollow needle tissue insertion force model Moore, Jason Z.; Malukhin, Kostyantyn; Shih, Albert J. ...
CIRP annals,
2011, 2011-00-00, Letnik:
60, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
In this study, a mechanistic approach using elementary cutting tool (ECT) edges of varying inclination and normal rake angles is demonstrated to be capable to predict hollow needle insertion force. A ...needle force model is developed and validated for the specific case of 11
gauge two-plane symmetric needles. Blades of varying inclination and rake angles are inserted into bovine liver to determine the specific force of initial tissue cutting for the given edge geometry; this information is applied to the ECT force model which is validated against experimental force results of hollow needles inserted into bovine liver.
The need for low-cost robust meso-scale "smart" robots (manipulators) that have no discrete parts (monolithic), no sensors ("self-sensing") and can be used in space-constrained systems, e.g., in ...microfactories, biomedical applications, etc., was the motivation for the current research. This study describes the design, fabrication and analysis of such a smart robot—a monolithic Micro/Meso Scale Manipulator (mMM), fabricated from Shape Memory Alloy powders (NiTi) by means of the laser-based Direct Metal Deposition (DMD) process. A first prototype, a functional part of the mMM - a SMA accordion spring type actuator was manufactured by DMD. The actuator provides a linear movement for the mMM due to the Shape Memory Effect (SME) property of SMAs. The One-Way SME was imposed on the spring actuator by a series of thermomechanical treatments. The SME drives the spring's movements due to the property of the SMAs to change their crystallographic structure and, therefore, shape, during heating or cooling. The characterization of the DMD manufactured material was done. SMAs change their crystallographic structure and/or shape (SME) when the phase transformation takes place in the material during its temperature and/or stress state change. A new mathematical model describing the phase transformation kinetics and a new analytical phase transformation function was developed. The phase transformation in SMAs causes electrical resistance change in the material. The motion, caused by the SME, can be controlled using the electrical resistance change as a feedback signal with no need for separate motion sensors. In the current work this "self-sensing" concept was explored and evaluated in an SMA wire based actuator and applied to the SMA spring based actuator. The dynamics of the sub-millimeter and millimeter scale motion of the SMA actuators was identified using physical models of the SMA wire based actuators. A new mathematical model of the motion of the SMA wire- and spring-based actuators was developed. It is planned to use the model of motion in the corresponding model of motion control of the actuators. An advanced prototype of the previously described SMA spring actuator was manufactured from a commercially available SMA (NiTi) ingot to experimentally verify the models of motion.
The essential steps and issues in the development of a Shape Memory Alloy (SMA) based multi-degrees-of-freedom monolithic manipulator are reflected upon. The use of Direct Metal Deposition (DMD) will ...be described for the manufacture of the manipulator’s structure followed by the exploration of the feasibility of the “self-sensing” functionality of the structure as a basis for the manipulator’s control. Finally, a synopsis of a new mathematical model of the kinetics of the temperature-induced phase transformation that was developed and its experimental verification will be given and shown that the analytical predictions closely follow the experimentally measured responses.
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