scholarly journals IGA Based Bi-Layer Fiber Angle Optimization Method for Variable Stiffness Composites

2020 ◽  
Vol 124 (1) ◽  
pp. 179-202
Author(s):  
Chao Mei ◽  
Qifu Wang ◽  
Chen Yu ◽  
Zhaohui Xia
Keyword(s):  
Variable Stiffness ◽  
Optimization Method ◽  
Fiber Angle ◽  
Layer Fiber

scholarly journals Variable stiffness identification and configuration optimization of industrial robots for machining tasks

2020 ◽  
Author(s):  
Jiachen Jiao ◽  
Wei Tian ◽  
Lin Zhang ◽  
Bo Li ◽  
Junshan Hu ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Optimization Methods ◽  
Optimization Method ◽  
Industrial Robots ◽  
Axial Stiffness ◽  
Configuration Optimization ◽  
Positional Accuracy ◽  
Stiffness Identification ◽  
Robot Stiffness ◽  
High Flexibility

Abstract Industrial robots are increasingly used in machining tasks because of their high flexibility and intelligence. However, the low structural stiffness of the robot seriously affects the positional accuracy and machining quality of robot operation equipment. Studying robot stiffness characteristics and optimization methods is an effective way to improve robot stiffness performance. Accordingly, aiming at the poor accuracy of stiffness modeling caused by approximating stiffness of each joint as constant, a variable stiffness identification method is proposed based on space gridding. Then, a task-oriented axial stiffness evaluation index is proposed to realize quantitative assessment of the stiffness performance in the machining direction. Besides, by analyzing the redundant kinematic characteristics of the robot machining system, a configuration optimization method is further come up with to maximize the index. For a large number of points or trajectory processing tasks, a configuration smoothing strategy is proposed to achieve fast acquisition of optimized configurations. Finally, experiments on a KR500 robot are conducted to verify the feasibility and validity of proposed stiffness identification and configuration optimization methods.

Topology optimization of linkage mechanisms simultaneously considering both kinematic and compliance characteristics

2020 ◽  
pp. 1-51
Author(s):  
Sang Min Han ◽  
Yoon Young Kim
Keyword(s):  
Topology Optimization ◽  
Kinematic Chain ◽  
Variable Stiffness ◽  
Optimization Method ◽  
Vehicle Suspension ◽  
Linkage Mechanism ◽  
Mechanism Synthesis ◽  
Kinematic Characteristics ◽  
Mechanism Kinematic ◽  
Topology Optimization Method

Abstract Studies on the topology optimization of linkage mechanisms have thus far focused mainly on mechanism synthesis considering only kinematic characteristics describing a desired path or motion. Here, we propose a new topology optimization method that synthesizes a linkage mechanism considering not only kinematic but also compliance (K&C) characteristics simultaneously, as compliance characteristics can also significantly affect the linkage mechanism performance; compliance characteristics dictate how elastic components, such as bushings in a vehicle suspension, are deformed by external forces. To achieve our objective, we use the spring-connected rigid block model (SBM) developed earlier for mechanism synthesis considering only kinematic characteristics, but we make it suitable for the simultaneous consideration of K&C characteristics during mechanism synthesis by making its zero-length springs multifunctional. Variable-stiffness springs were used to identify the mechanism kinematic configuration only, but now in the proposed approach, they serve to determine not only the mechanism kinematic configuration but also the compliance element distribution. In particular, the ground-anchoring springs used to anchor a linkage mechanism to the ground are functionalized to simulate actual bushings as well as to identify the desired linkage kinematic chain. After the proposed formulation and numerical implementation are presented, case studies are considered. In particular, the effectiveness of the proposed method is demonstrated with a simplified two-dimensional vehicle suspension design problem. This study is expected to pave the way to advance the topology optimization method for general linkage mechanisms whenever K&C characteristics must be simultaneously considered for mechanism synthesis.

Generating realistic laminate fiber angle distributions for optimal variable stiffness laminates

2012 ◽  
Vol 43 (2) ◽  
pp. 354-360 ◽  
Author(s):  
Julien M.J.F. van Campen ◽  
Christos Kassapoglou ◽  
Zafer Gürdal
Keyword(s):  
Variable Stiffness ◽  
Fiber Angle

scholarly journals Variable Stiffness Mechanism for the Reduction of Cutting Forces in Robotic Deburring

2021 ◽  
Vol 11 (6) ◽  
pp. 2883
Author(s):  
Matteo Bottin ◽  
Silvio Cocuzza ◽  
Matteo Massaro
Keyword(s):  
Conceptual Design ◽  
Cutting Forces ◽  
Variable Stiffness ◽  
Optimization Method ◽  
The Other ◽  
Design Parameters ◽  
Test Cases ◽  
Dynamic Simulations ◽  
Main Design ◽  
The One

One of the main issues related to robotic deburring is that the tool can get damaged or stopped when the burr thickness exceeds a certain threshold. The aim of this work is to devise a mechanism that can reduce cutting forces automatically, in the event that the burr is too high, and is able to return to the baseline configuration when the burr thickness is acceptable again. On the one hand, in normal cutting conditions, the mechanism should have high stiffness to ensure high cutting precision. On the other hand, when the burr is too high the mechanism should exploit its compliance to reduce the cutting forces and, as a consequence, a second cutting cycle will be necessary to completely remove the burr. After the conceptual design of the mechanism and the specification of the desired stiffness curve, the main design parameters of the system are derived thanks to an optimization method. The effectiveness of the proposed mechanism is verified by means of dynamic simulations using selected test cases. A reduction up to 60% of the cutting forces is obtained, considering a steel burr up to 6 mm high.

scholarly journals Multi-Objective Optimization of Variable-Stiffness Composites Fabricated by Tailored Fiber Placement Machine

2019 ◽  
Vol 2 (1) ◽  
pp. 14-18
Author(s):  
Shinya Honda
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Variable Stiffness ◽  
Optimization Method ◽  
Pareto Optimum ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Fiber Placement ◽  
Curvilinear Fibers ◽  
Placement Machine

A multi-objective optimization method for the laminated composite fabricated by a tailored fiber placement machine that is an application of embroidering machine is presented. The mechanical properties of composite with curvilinear fibers including stiffness, volume fraction, and density are variable depending on curvatures of fibers. The present study first measures the relation between curvatures and mechanical properties. The measured results indicate that the stiffness of composite decreases linearly as the curvature increases. Then, the obtained relation is applied to the multi-objective optimization where the maximum principal strain and magnitude of curvature are employed as objective functions. Obtained Pareto optimum solutions are widely distributed ranging from the solutions with curvilinear fibers to those with straight fibers, and the curvilinear fiber has still advantages over straight fiber even its weakened stiffness.

Synthesis of Gear-Linkage Mechanisms by Topology Optimization

2018 ◽  
Author(s):  
Neung Hwan Yim ◽  
Seok Won Kang ◽  
Yoon Young Kim
Keyword(s):  
Topology Optimization ◽  
Design Space ◽  
Synthesis Method ◽  
Variable Stiffness ◽  
Optimization Methods ◽  
Optimization Method ◽  
Planar Mechanisms ◽  
Gear Design ◽  
Linkage Design ◽  
Gradient Based

This work is concerned with a new mechanism synthesis method for the simultaneous determination of the type, number and dimension of mechanisms by topology optimization. Earlier topology optimization methods can synthesize linkage mechanisms that consist only of links and joints. The proposed synthesis method is a gradient-based topology optimization method useful for the synthesis of planar mechanisms consisting of linkages and gears. To formulate the topology optimization based method, we propose two superposed design spaces as a ground structure: the linkage and gear design spaces. The gear design space is discretized by newly proposed gear blocks while the linkage design space by rigid blocks. The zero-length springs with variable stiffness are used to control the connectivity of blocks, which in turns determines the configuration of the synthesized mechanism. After the proposed topology-optimization-based synthesis formulation is presented, its effectiveness and validity are checked with various synthesis examples.

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