Design of a Partially Compliant, Three-Phalanx Underactuated Prosthetic Finger

2015 ◽  
Author(s):  
Marco W. M. Groenewegen ◽  
Milton E. Aguirre ◽  
Just L. Herder
Keyword(s):  
Design Method ◽  
Experimental Testing ◽  
High Strength ◽  
Robotic Hand ◽  
Genetic Optimization ◽  
Element Analysis ◽  
Acceptable Error ◽  
Rigid Body Model ◽  
Bending Stresses ◽  
Prosthetic Finger

Advanced robotic hand prostheses are praised for their impressive robust and fine grasping capabilities generated from intricate systems. Nevertheless, a high demand remains for grasping mechanisms that are mechanically simple, lightweight, and cheap to produce, easy to assemble and low in maintenance costs. This paper presents the design of a partially compliant underactuated finger to demonstrate the feasibility of achieving these rigorous requirements. The conceptual topology of the three phalanx finger is selected based on competitive analysis. Employing Pseudo-Rigid Body Model and Finite Element Analysis, a genetic optimization problem is formulated to minimize bending stresses within compliant flexures. The result is a fully functional demonstrator capable of flexing 180° in finger rotation. The prototype is fabricated from flexible high strength nylon and requires no assembly steps beyond 3D printing. Experimental testing verifies the design method with an acceptable error of < 5%.

Kinematic Synthesis of a D-Drive MEMS Device With Rigid-Body Replacement Method

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Paolo Sanò ◽  
Matteo Verotti ◽  
Paolo Bosetti ◽  
Nicola P. Belfiore
Keyword(s):  
Rigid Body ◽  
Experimental Testing ◽  
Micro Electro Mechanical System ◽  
Element Analysis ◽  
Kinematic Synthesis ◽  
Replacement Method ◽  
Rigid Body Model ◽  
Mems Device ◽  
Conjugate Surfaces ◽  
Line Path

In this paper, a microsystem with prescribed functional capabilities is designed and simulated. In particular, the development of a straight line path generator micro electro mechanical system (MEMS) device is presented. A new procedure is suggested for avoiding branch or circuit problems in the kinematic synthesis problem. Then, Ball's point detection is used to validate the obtained pseudo-rigid body model (PRBM). A compliant MEMS device is obtained from the PRBM through the rigid-body replacement method by making use of conjugate surfaces flexure hinges (CSFHs). Finally, the functional capability of the device is investigated by means of finite element analysis (FEA) simulations and experimental testing at the macroscale.

Design Process of Durable and Lightweight Rally Car Frame from Ultra-High Strength Stainless Steel

2018 ◽  
Vol 786 ◽  
pp. 325-332 ◽  
Author(s):  
Terho Iso-Junno ◽  
Henri Niemi ◽  
Jarmo Mäkikangas ◽  
Kari Mäntyjärvi
Keyword(s):  
Design Process ◽  
Design Method ◽  
High Strength ◽  
Short Time Period ◽  
Element Analysis ◽  
Design Iteration ◽  
Time Period ◽  
Ultra High Strength Steel ◽  
Key Steps ◽  
Short Time

To get all outstanding mechanical properties from ultra-high strength steel (UHSS) transformed into a lightweight and durable product, a comprehensive design process must be performed. The general DFMA method has been extended to get good design solutions with limited designer resources and within a relative short time period. Key steps of the extended DFMA design process are innovative brainstorming, the agile utilization of the optimization software, the heavy use of finite element analysis and fast design iteration. In this paper, the modified DFMA design method is described step by step. This method has been successfully used in the design process of the small lightweight rally car frame. The design process of the rally car is introduced as a case example of implementation of the extended DFMA.

Strength Optimization of Infant Pop-Up Seat Frame Using Discrete Material and Thickness Optimization

2021 ◽  
Vol 11 (3) ◽  
pp. 1-20
Author(s):  
YeongJo Ju ◽  
Euysik Jeon
Keyword(s):  
Optimal Design ◽  
High Strength Steel ◽  
Design Method ◽  
High Strength ◽  
Optimization Method ◽  
Design Criterion ◽  
Thickness Optimization ◽  
Element Analysis ◽  
Strength Design ◽  
Seat Frame

In this paper, the authors proposed an optimal design method for the strength design of infant pop-up seat frame combined with rear seats for infants, children, and adults, not removable booster seats or car seats. Frame strength design was performed using discrete material and thickness optimization (DMTO) method considering high strength steel (HSS) and advanced high strength steel (AHSS). Structural design using the Section 4 link mechanism was performed, and the weakness of the seat frame due to static load was confirmed through finite element analysis. An optimal design criterion was established by carrying out a case study to derive the limiting conditions according to static and dynamic loads. In consideration of these criteria, the optimal design according to d-optimal and discrete Latin-hypercube (DLH) was performed among the design of experiments (DOE). And the strength of the pop-up seat frame for infants according to each DOE was checked, and the strength optimization method was suggested by comparing the lightweight ratio.

An Improved Size, Matching, and Scaling Method for the Design of Deterministic Mesoscale Truss Structures

2011 ◽  
Author(s):  
Patrick S. Chang ◽  
David W. Rosen
Keyword(s):  
High Performance ◽  
Design Method ◽  
Weight Ratio ◽  
High Strength ◽  
Original Method ◽  
Topological Optimization ◽  
Truss Structures ◽  
Scaling Method ◽  
Element Analysis ◽  
And Performance

Mesoscale truss structures are cellular structures that have support elements on the order of centimeters. These structures are engineered for high performance and have applications in industries where a high strength-to-weight ratio is desired. However, design of mesoscale truss structures currently requires some form of topological optimization that slows the design process. In previous research, a new Size, Matching and Scaling method was presented that eliminated the need for topological optimization by using a solid-body finite element analysis combined with a library of lattice configurations to generate topologies. When compared to topological optimization, results were favorable: design times were significantly reduced and performance results were comparable. In this paper, we present a modified Size Matching and Scaling design method that addresses key issues in the original method. Firstly, we outline an improve methodology. Secondly, we expand the library of configurations in order to improve lattice performance. Finally, we test the updated method and library against design examples.

Numerical Study of Round-Robin Tests on the Split Hopkinson Pressure Bar Technique

2013 ◽  
Vol 535-536 ◽  
pp. 518-521 ◽  
Author(s):  
Muhammad A. Kariem ◽  
Dong Ruan ◽  
John H. Beynon
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
High Strength ◽  
Round Robin ◽  
Hopkinson Pressure Bar ◽  
Element Analysis ◽  
Acceptable Error ◽  
Aisi 4140 ◽  
Split Hopkinson ◽  
Pressure Bar

It is known that the split Hopkinson pressure bar (SHPB) technique has not been standardised yet. The standardised SHPB technique is necessary in order to provide guidelines for determining the intrinsic material properties. This paper examines whether consistent results can be achieved from various sets of SHPBs. Finite element analysis has been conducted using ANSYS/LS-DYNA. Numerical simulation of the round-robin tests was conducted to study the consistency of results for OFHC copper, which were obtained from three sets of apparatus, namely: 12.7 mm diameter SHPB made from the AISI 4140 steel, 13 mm diameter SHPB made from the high strength steel (HSS) and 14.5 mm diameter SHPB made from maraging steel 350 (AISI 18Ni). The current study shows that consistent flow stresses (within an acceptable error of 2.5%) were obtained from those three sets of SHPBs, which indicates the possibility of SHPB standardisation in the future.

A Study on the Application of Large Aluminum Hollow Extrusion Profiles to Ship Structures

1999 ◽  
Vol 15 (03) ◽  
pp. 179-190
Author(s):  
Seung II Seo ◽  
Kon Ho Son ◽  
Jae Hong Park
Keyword(s):  
High Speed ◽  
Plate Theory ◽  
Design Method ◽  
Structural Characteristics ◽  
High Strength ◽  
Normal Pressure ◽  
Labor Cost ◽  
Element Analysis ◽  
Plate Buckling ◽  
Structural Behaviors

Aluminum is much useful material for high speed light crafts due to high strength and light weight. Large aluminum hollow extrusion profiles have another merits such as easy production of complicated shapes, reduction of welding and cutting lines, easy fabrication, high quality and labor cost-down. In this paper, a design method for aluminum hollow extrusion profiles was developed. Detailed finite element analysis was carried out to comprehend the structural behaviors of the hollow extrusion profiles subjected to normal pressure and compression. Simple formulas were proposed to analyze structural characteristics of the hollow extrusion profiles based on orthotropic plate theory and plate buckling theory. By comparison with the detailed analysis results, it was shown that simple formulas have good accuracy and efficiency. For practical application of the proposed simple formulas, optimization for reduction of weight under strength and production constraints was carried out and useful results were obtained.

scholarly journals Failure Analysis on a Collapsed Flat Cover of an Adjustable Ballast Tank Used in Deep-Sea Submersibles

2019 ◽  
Vol 9 (23) ◽  
pp. 5258
Author(s):  
Fang Wang ◽  
Mian Wu ◽  
Genqi Tian ◽  
Zhe Jiang ◽  
Shun Zhang ◽  
...  
Keyword(s):  
Deep Sea ◽  
Material Selection ◽  
High Strength ◽  
External Pressure ◽  
Element Analysis ◽  
Ballast Tank ◽  
Material Inhomogeneity ◽  
Comprehensive Properties ◽  
Ultimate Cause ◽  
Flat Cover

A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably below the design limit of the adjustable ballast tank. The failure may have been caused by material properties that may be defective, the possible stress concentration resulting from design/processing, or inappropriate installation method. The present paper focuses on the visual inspections of the material inhomogeneity, ultimate cause of the collapse of the flat cover in pressure testing, and finite element analysis. Special attention is paid to the toughness characteristics of the material. The present study demonstrates the importance of material selection for engineering components based on the comprehensive properties of the materials.

Design of a Single-Acting Constant-Force Actuator Based on Dielectric Elastomers

2008 ◽  
Author(s):  
Giovanni Berselli ◽  
Rocco Vertechy ◽  
Gabriele Vassura ◽  
Vincenzo Parenti Castelli
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compliant Mechanism ◽  
Structural Parameters ◽  
Dielectric Elastomer ◽  
Constant Force ◽  
Element Analysis ◽  
Body Model ◽  
Rigid Body Model ◽  
Supporting Frame

The interest in actuators based on dielectric elastomer films as a promising technology in robotic and mechatronic applications is increasing. The overall actuator performances are influenced by the design of both the active film and the film supporting frame. This paper presents a single-acting actuator which is capable of supplying a constant force over a given range of motion. The actuator is obtained by coupling a rectangular film of silicone dielectric elastomer with a monolithic frame designed to suitably modify the force generated by the dielectric elastomer film. The frame is a fully compliant mechanism whose main structural parameters are calculated using a pseudo-rigid-body model and then verified by finite element analysis. Simulations show promising performance of the proposed actuator.

scholarly journals Design of a Unique Device for Residual Stresses Quantification by the Drilling Method Combining the PhotoStress and Digital Image Correlation

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 314
Author(s):  
Miroslav Pástor ◽  
Martin Hagara ◽  
Ivan Virgala ◽  
Adam Kaľavský ◽  
Alžbeta Sapietová ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Experimental Testing ◽  
Digital Processing ◽  
Image Correlation ◽  
Optical Systems ◽  
Hole Drilling ◽  
Element Analysis ◽  
Thin Specimen ◽  
Comparison Of The Results

This paper presents a uniquely designed device combining the hole-drilling technique with two optical systems based on the PhotoStress and digital image correlation (DIC) method, where the digital image correlation system moves with the cutting tool. The authors aimed to verify whether the accuracy of the drilled hole according to ASTM E837-13a standard and the positioning accuracy of the device were sufficient to achieve accurate results. The experimental testing was performed on a thin specimen made from strain sensitive coating PS-1D, which allowed comparison of the results obtained by both methods. Although application of the PhotoStress method allows analysis of the strains at the edge of the cut hole, it requires a lot of experimenter’s practical skills to assess the results correctly. On the other hand, the DIC method allows digital processing of the measured data. However, the problem is not only to determine the data at the edge of the hole, the results also significantly depend on the smoothing levels used. The quantitative comparison of the results obtained was performed using finite element analysis.

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