Characterization and control of plastic deformation in mesoscale premolded components to realize in-mold assembled mesoscale revolute joints

2008 ◽  
Vol 49 (2) ◽  
pp. 293-304 ◽  
Author(s):  
Arvind Ananthanarayanan ◽  
Satyandra K. Gupta ◽  
Hugh A. Bruck
Keyword(s):  
Plastic Deformation ◽  
Revolute Joints ◽  
And Control

Design and Analysis of Reduced Degree of Freedom Modular Snake Robot

2017 ◽  
Author(s):  
Peter Racioppo ◽  
Wael Saab ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Three Dimensional ◽  
Cross Sectional ◽  
Design Synthesis ◽  
Snake Robot ◽  
Routing Schemes ◽  
Revolute Joints ◽  
Modular Units ◽  
A Chain ◽  
The Moment ◽  
And Control

This paper presents the design and analysis of an underactuated, cable driven mechanism for use in a modular robotic snake. The proposed mechanism is composed of a chain of rigid links that rotate on parallel revolute joints and are actuated by antagonistic cable pairs and a multi-radius pulley. This design aims to minimize the cross sectional area of cable actuated robotic snakes and eliminate undesirable nonlinearities in cable displacements. A distinctive feature of this underactuated mechanism is that it allows planar serpentine locomotion to be accomplished with only two modular units, improving the snake’s ability to conform to desired curvature profiles and minimizing the control complexity involved in snake locomotion. First, the detailed mechanism and cable routing scheme are presented, after which the kinematics and dynamics of the system are derived and a comparative analysis of cable routing schemes is performed, to assist with design synthesis and control. The moment of inertia of the mechanism is modeled, for future use in the implementation of three-dimensional modes of snake motion. Finally, a planar locomotion strategy for snake robots is devised, demonstrated in simulation, and compared with previous studies.

Modeling and Characterization to Minimize Effects of Melt Flow Fronts on Premolded Component Deformation During In-Mold Assembly of Mesoscale Revolute Joints

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
A. Ananthanarayanan ◽  
S. K. Gupta ◽  
H. A. Bruck
Keyword(s):  
Plastic Deformation ◽  
High Speed ◽  
Polymer Melt ◽  
Production Costs ◽  
Melt Flow ◽  
Flow Front ◽  
Melting Temperatures ◽  
Second Stage ◽  
Revolute Joints ◽  
Front Position

In-mold assembly can be used to create mesoscale articulating polymeric joints that enable the miniaturization of devices, reduction in production costs, and increase in throughput. One of the major challenges in miniaturizing devices using the in-mold assembly is to develop appropriate characterization techniques and modeling approaches for the interaction between polymer melt flow fronts and premolded components. When a high speed, high temperature second stage melt comes in contact with a premolded mesoscale component that has similar melting temperatures, the premolded component can experience a significant plastic deformation due to the thermal softening and the force associated with impingement of the melt flow front. In our previous work, we developed methods to inhibit the plastic deformation by supporting the ends of the mesoscale premolded components. In this paper, we present an alternative strategy for controlling premolded component deformations. This involves a mesoscale in-mold assembly strategy that has a multigate mold design for bidirectional filling. This strategy permits in-mold assembly using polymers with comparable melting points. This paper demonstrates the technical feasibility of manufacturing in-mold-assembled mesoscale revolute joints using this bidirectional filling strategy. An experimental technique was developed for characterizing the transient impact force of the melt flow front on premolded components inside of a mold. The experimental data were used to validate a new computational model for predicting the effects of the melt flow front position in order to minimize the plastic deformation of premolded component using the bidirectional filling strategy. This paper also investigates the effects of the flow front position on the force applied on the premolded component and its corresponding plastic deformation.

Redundancy utilization for obstacle avoidance of planar robot manipulators

1997 ◽  
Vol 211 (6) ◽  
pp. 463-475 ◽  
Author(s):  
U Sezgin ◽  
L D Seneviratne ◽  
S W E Earles
Keyword(s):  
Obstacle Avoidance ◽  
Computer Simulations ◽  
Redundant Manipulators ◽  
Control Points ◽  
Kinematic Redundancy ◽  
End Effector ◽  
Revolute Joints ◽  
Planar Robot ◽  
And Control ◽  
Configuration Control

Two obstacle avoidance criteria are developed, utilizing the kinematic redundancy of serial redundant manipulators having revolute joints and tracking pre-determined end effector paths. The first criterion is based on the instantaneous distances between certain selected points along the manipulator, called configuration control points (CCP), and the vertices of the obstacles. The optimized joint configurations are obtained by maximizing these distances. Thus, the links of the manipulator are configured away from the obstacles. The second criterion uses a different approach, and is based on Voronoi boundaries representing the equidistant paths between two obstacles. The optimized joint configurations are obtained by minimizing the distances between the CCP and control points selected on the Voronoi boundaries. The validities of the criteria are demonstrated through computer simulations.

Modelling of Tandem Rolling Mills Including Tensional Stress Propagation

1993 ◽  
Vol 207 (2) ◽  
pp. 143-150 ◽  
Author(s):  
T Kong ◽  
D C H Yang
Keyword(s):  
Plastic Deformation ◽  
Dynamic Simulation ◽  
Work Roll ◽  
Rolling Mills ◽  
Damping Effect ◽  
Stress Propagation ◽  
Simulation Results ◽  
Tensional Stress ◽  
And Control ◽  
Dynamic Phenomena

This paper presents an analytical model for dynamic simulation of the tandem mills. The model is a comprehensive one which includes the consideration of elasticity and damping effect at the rolls, plastic deformation at the bite region, stress propagation tensional waves among stands, external scroll force at the back-up rolls and torsional vibration of the work roll. Simulation results show that chatter and other dynamic phenomena can successfully be predicted. It is believed that this model will be useful in the design and control of tandem mills.

Analysis of Plastic Deformation in Metal-Ceramic Nanolayers During Cyclic Indentation

2012 ◽  
Author(s):  
C. B. Blada ◽  
Y.-L. Shen
Keyword(s):  
Plastic Deformation ◽  
Transient Behavior ◽  
Primary Objective ◽  
Cyclic Plasticity ◽  
Rate Dependent ◽  
Diamond Indenter ◽  
Metal Ceramic ◽  
Elastic Loading ◽  
Cyclic Indentation ◽  
And Control

The indentation behavior of metal/ceramic nanolayers is studied, with attention devoted to cyclic response under fixed maximum and minimum indentation loads. The primary objective is to examine the evolving plastic deformation in the ductile metal constrained by the hard ceramic layers. The model consists of alternating aluminum (Al) and silicon carbide (SiC) thin films on a silicon substrate, with the Al/SiC layered structure being indented by a diamond indenter. The rate-dependent viscoplastic response of Al is taken into account in the numerical model. It is shown that plastic deformation in the ductile Al layers continues to occur during the unloading phase of the first cycle, as well as during subsequent reload/unload processes. The cyclic plasticity results in an open load-displacement loop, and the indenter continues to move deeper with each cycle. For the control model of a homogeneous Al film, there is no hysteresis loop and the transient behavior soon approaches stabilization, showing repetitive elastic loading/unloading. The modeling results are also compared with cyclic nanoindentation experiments conducted on the same metal-ceramic multilayer system and control specimen.

Thermo Mechanical Analysis of Ultrasonic Welding of Metal Joints Under Different Control Parameters

2015 ◽  
Author(s):  
Dalong Yi ◽  
Hui Zhang ◽  
Lili Zheng
Keyword(s):  
Plastic Deformation ◽  
Process Parameters ◽  
Welding Process ◽  
Element Model ◽  
Mechanical Analysis ◽  
Ultrasonic Welding ◽  
Control Parameters ◽  
Bond Quality ◽  
Atom Diffusion ◽  
And Control

Ultrasonic welding is a complex process combining the processes of interface friction, heat transfer, plastic deformation heating, and atom diffusion and so on. Even though much work has been performed to understand ultrasonic welding process, the key characteristic process parameters of ultrasonic welding process and the key control parameters for the bond quality are still questions. Based on the interactions of bond factors and previous research of ultrasonic welding process, we believe that plastic deformation and temperature which represent the energy and strain condition at bonding interface are the key process parameters related to bond. A 3-D thermal-mechanical finite element model is built to analyze the thermal and mechanical files of ultrasonic welding process of two types of aluminum alloys under different control parameters. A possible mechanism between bond quality and control parameters based on max temperature and max plastic deformation of temperature-strain map of simulation is presented.

scholarly journals Position and Singularity Analysis of a Class of Planar Parallel Manipulators with a Reconfigurable End-Effector

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Tommaso Marchi ◽  
Giovanni Mottola ◽  
Josep M. Porta ◽  
Federico Thomas ◽  
Marco Carricato
Keyword(s):  
Inverse Kinematics ◽  
Kinematic Chain ◽  
Experimental Tests ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
End Effector ◽  
Revolute Joints ◽  
A Chain ◽  
And Control

Parallel robots with configurable platforms are a class of robots in which the end-effector has an inner mobility, so that its overall shape can be reconfigured: in most cases, the end-effector is thus a closed-loop kinematic chain composed of rigid links. These robots have a greater flexibility in their motion and control with respect to rigid-platform parallel architectures, but their kinematics is more challenging to analyze. In our work, we consider n-RRR planar configurable robots, in which the end-effector is a chain composed of n links and revolute joints, and is controlled by n rotary actuators located on the base of the mechanism. In particular, we study the geometrical design of such robots and their direct and inverse kinematics for n=4, n=5 and n=6; we employ the bilateration method, which can simplify the kinematic analysis and allows us to generalize the approach and the results obtained for the 3-RRR mechanism to n-RRR robots (with n>3). Then, we study the singularity configurations of these robot architectures. Finally, we present the results from experimental tests that have been performed on a 5–RRR robot prototype.

scholarly journals Strength of multilayer metal joints «shaft-sleeve-hub» of rotorcrafts obtained by plastic deformation

2021 ◽  
Vol 2131 (5) ◽  
pp. 052015
Author(s):  
S Lesniak ◽  
V Dudnik ◽  
M Borowy ◽  
O Lesniak
Keyword(s):  
Plastic Deformation ◽  
Control Systems ◽  
Contact Pressure ◽  
Adhesion Strength ◽  
Wall Thickness ◽  
Traction Force ◽  
Pressing Force ◽  
Frictional Forces ◽  
And Control ◽  
Multilayer Metal

Abstract Metal multilayer joints are used in the production and repair of transmission parts and control systems of rotorcrafts with intensively wearing surfaces in the form of smooth closed cylindrical and conical holes. The article describes two types of connections: rolled sleeve - hub and shaft - rolled sleeve - hub. The adhesion strength of the joints depends on the frictional forces that prevent the sleeve from displacing relative to the hub. The traction strength is determined by measuring the pressing force and the torque. It depends on the relative tension. An increase in the force of pressing the joint occurs with an increase in the relative tension of mandrel, in proportion to the hardening of the material. The smaller hub wall thickness leads to the more active effect of its springback to the foundation of contact pressure and an increasing of the traction force. Experiments have shown that the forces and moments of traction depend on the angle of the intake cone and the width of the cylindrical tape of the mandrel.

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