scholarly journals Programmable Kirigami: Cutting and Folding in Science, Technology and Architecture

2019 ◽  
Author(s):  
Jingyang Liu ◽  
Grace Chuang ◽  
Hun Chun Sang ◽  
Jenny E. Sabin
Keyword(s):  
Multiple Scales ◽  
Three Dimensional ◽  
Computational Design ◽  
Element Analysis ◽  
Human Scale ◽  
Wide Range ◽  
2D Pattern ◽  
Novel Method ◽  
Doubly Curved ◽  
Forward Process

Abstract This paper investigates the potential of kirigami-folding with the addition of strategically placed cuts at multiple scales through both computational design and physical prototyping. The study develops a novel method and workflow for generating two-dimensional (2D) kirigami patterns developed from doubly curved three-dimensional (3D) surfaces (Inverse process). Corresponding simulations of the kirigami folding motion from 2D pattern to 3D goal shape are presented (Forward process). The workflow is based on a reciprocal feedback loop including computational design, finite element analysis, dynamic simulation and physical prototyping. Extended from previous research on kirigami geometry, this paper incorporates material properties into the folding process and successfully develops active kirigami models from the DNA scale to human scale. The results presented in this paper provide an attractive method for kirigami design and fabrication with a wide range of scales and applications.

Incorporating Neural Network Material Models Within Finite Element Analysis for Rheological Behavior Prediction

2006 ◽  
Vol 129 (1) ◽  
pp. 58-65 ◽  
Author(s):  
B. Scott Kessler ◽  
A. Sherif El-Gizawy ◽  
Douglas E. Smith
Keyword(s):  
Finite Element ◽  
Effective Means ◽  
Element Model ◽  
Operating Conditions ◽  
Behavior Prediction ◽  
Element Analysis ◽  
Material Models ◽  
Rheological Models ◽  
Wide Range ◽  
Novel Method

The accuracy of a finite element model for design and analysis of a metal forging operation is limited by the incorporated material model’s ability to predict deformation behavior over a wide range of operating conditions. Current rheological models prove deficient in several respects due to the difficulty in establishing complicated relations between many parameters. More recently, artificial neural networks (ANN) have been suggested as an effective means to overcome these difficulties. To this end, a robust ANN with the ability to determine flow stresses based on strain, strain rate, and temperature is developed and linked with finite element code. Comparisons of this novel method with conventional means are carried out to demonstrate the advantages of this approach.

scholarly journals Virtual paleontology: computer-aided analysis of fossil form and function

2014 ◽  
Vol 88 (4) ◽  
pp. 633-635 ◽  
Author(s):  
Imran A. Rahman ◽  
Selena Y. Smith
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Fossil Plants ◽  
Element Analysis ◽  
X Ray ◽  
Form And Function ◽  
Wide Range ◽  
History Of ◽  
Micro Tomography ◽  
And Function

‘Virtual paleontology’ entails the use of computational methods to assist in the three-dimensional (3-D) visualization and analysis of fossils, and has emerged as a powerful approach for research on the history of life. Three-dimensional imaging techniques allow poorly understood or previously unknown anatomies of fossil plants, invertebrates, and vertebrates, as well as microfossils and trace fossils, to be described in much greater detail than formerly possible, and are applicable to a wide range of preservation types and specimen sizes (Table 1). These methods include non-destructive high-resolution scanning technologies such as conventional X-ray micro-tomography and synchrotron-based X-ray tomography. In addition, form and function can be rigorously investigated through quantitative analysis of computer models, for example finite-element analysis.

scholarly journals Noise Reduction Design with Trapezoidal Back-EMF and Asymmetric Air-Gap for Single-Phase BLDC Refrigerator Cooling Fan Motor

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5467
Author(s):  
Jin-Hwan Lee ◽  
Sang-Yong Jung
Keyword(s):  
Single Phase ◽  
Three Dimensional ◽  
Torque Ripple ◽  
Air Gap ◽  
Manufacturing Cost ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Novel Method ◽  
The Dead ◽  
Three Dimensional Finite Element

In this study, a novel method for reducing the noise generated by single-phase claw-pole motors employed as refrigerator fan blowers is proposed. A single-phase claw-pole motor has the advantages of low manufacturing cost, easy manufacturing, and a high number of turns. However, in such motors, current delays occur owing to a high inductance; therefore, it is necessary to merge the back-electromotive force and current phases into the same phase using the phase advance method. Additionally, a single-phase motor exhibits dead torque and zero torque at an electrical angle of 180° owing to its electrical characteristics, and the dead torque deteriorates the average torque and torque ripple characteristics of the motor. In this study, a novel method is proposed to make the air gap asymmetrical by tilting the claw to reduce the noise generated by single-phase claw-pole motors. An asymmetric air gap allows the cogging torque to eliminate the dead torque caused by alignment torques, causing the torque ripple to decrease. To validate the effectiveness of the proposed method, the proposed model is compared with a base model via three-dimensional finite element analysis. Furthermore, the two models are manufactured and a noise test is conducted in an anechoic chamber to compare the noise difference between the two models.

scholarly journals INTEGRATION OF CAD AND CAE IN SME’S FOR PRODUCT DEVELOPMENT

2012 ◽  
pp. 221-223
Author(s):  
PRASHANT B. SAGAR ◽  
MADHUKAR R. NAGARE
Keyword(s):  
Product Development ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Product Development Process ◽  
Element Analysis ◽  
Manufacturing Enterprises ◽  
Cad System ◽  
Small Manufacturer ◽  
Wide Range ◽  
Computer Aided

Small manufacturing enterprises face a number of challenges when integrating computer aided design (CAD) tools and computer-aided engineering (CAE) tools into their design processes. One of the most significant challenges is interoperability across the wide range of commercial CAD and CAE tools. Although many of these tools support industry data standards and claim to be interoperable, the connection between them is not seamless. This paper summarizes studies of tool integration activities at one small manufacturer. The paper shows the enhancement of the product development process resulting from replacement of a two dimensional CAD system with a three-dimensional CAD system and creation of an inhouse capability to perform finite element analysis (FEA), replacing analysis that had previously been outsourced. As a result of these experiences, the manufacturer learned that improved productivity and superior designs could be obtained by integrating analysis into the design process at the earlier stages of conceptual and preliminary design.

scholarly journals Analysis and Mitigation of Stray Capacitance Effects in Resistive High-Voltage Dividers

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2278
Author(s):  
Jordi-Roger Riba ◽  
Francesca Capelli ◽  
Manuel Moreno-Eguilaz
Keyword(s):  
High Voltage ◽  
Three Dimensional ◽  
Alternating Current ◽  
Stray Capacitance ◽  
Element Analysis ◽  
Wide Range ◽  
Resistive Divider ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Capacitance Effects

This work analyzes the effects of the parasitic or stray distributed capacitance to ground in high-voltage environments and assesses the effectiveness of different corrective actions to minimize such effects. To this end, the stray capacitance of a 130 kV RMS high-voltage resistive divider is studied because it can severely influence the behavior of such devices when operating under alternating current or transient conditions. The stray capacitance is calculated by means of three-dimensional finite element analysis (FEA) simulations. Different laboratory experiments under direct current (DC) and alternating current (AC) supply are conducted to corroborate the theoretical findings, and different possibilities to mitigate stray capacitance effects are analyzed and discussed. The effects of the capacitance are important in applications, such as large electrical machines including transformers, motors, and generators or in high-voltage applications involving voltage dividers, conductors or insulator strings, among others. The paper also proves the usefulness of FEA simulations in predicting the stray capacitance, since they can deal with a wide range of configurations and allow determining the effectiveness of different corrective configurations.

A three‐dimensional strain concentration equation for countersunk holes

2008 ◽  
Vol 43 (2) ◽  
pp. 75-85 ◽  
Author(s):  
A Bhargava ◽  
K N Shivakumar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Concentration Factor ◽  
Three Dimensional ◽  
Structural Elements ◽  
Element Analysis ◽  
Strain Concentration ◽  
Wide Range ◽  
Dimensional Equation ◽  
Concentration Equation

Countersunk rivets are used to join components to achieve aerodynamic or hydrodynamic surfaces. At countersunk holes, three‐dimensional stress and strain concentrations occur. Previously, the present authors developed a three‐dimensional equation for the stress concentration factor Kt through a detailed finite element analysis. This paper extends the study to include an equation for three‐dimensional strain concentration factor Ktε using a similar approach. The resulting equation was verified by finite element analysis for a wide range of countersunk hole configurations and plate sizes. Results showed that the maximum strain concentration is at the countersunk edge. The developed equation is within 5 per cent of the finite element results for all practical cases. It was also found that the Ktε and Kt expressions are similar and Ktε≥ Kt. The maximum difference between the two is 8 per cent (for = 0.3) or 2 for straight‐shank holes and about 2/2 for countersunk holes. The proposed equation is a valuable tool for strain‐based design of structural elements.

Development of Bionic Auditory Membrane With Non-Uniform Thickness for Acoustic Sensor With Wide-Range Frequency Selectivity

2011 ◽  
Author(s):  
Hirofumi Shintaku ◽  
Satoyuki Kawano
Keyword(s):  
Acoustic Wave ◽  
Three Dimensional ◽  
Frequency Selectivity ◽  
Acoustic Sensor ◽  
Uniform Thickness ◽  
Negative Photoresist ◽  
Wide Range ◽  
Novel Method ◽  
Eigen Frequencies ◽  
Photolithography Process

In this study, we propose a bionic auditory membrane (BAM) which realizes the wide-range frequency selectivity by non-uniform thick structure. BAM developed here is an acoustic sensor consisting of flexible bridges that vibrate by applying acoustic wave. BAM works as frequency analyzer via resonance of vibration; the eigen frequencies of bridges are changed by varying the dimensions such as the length and the thickness. To overcome difficulties in fabricating three-dimensional structures by conventional microfabrication, a novel method was developed using a grayscale lithography and a negative photoresist. The thicknesses of bridges are varied by different tones of grayscale patterns in a photomask. BAM consisting of 64 bridges with various thicknesses from 6.6 μm to 49 μm is successfully fabricated and integrated in 2.0 mm × 30 mm area by single photolithography process. The eigen frequencies of the vibration were measured in air. The results revealed that the range of the frequency selectivity is from 16.7 kHz to 502 kHz, which is drastically widened by the non-uniform thick bridges compared with the uniform ones.

Simplified Stress Categorization Using a Single Linear Elastic Analysis

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
M. M. Hossain ◽  
W. D. Reinhardt ◽  
R. Seshadri
Keyword(s):  
Pressure Vessel ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Limit Load ◽  
Element Analysis ◽  
Elastic Stresses ◽  
Linear Elastic ◽  
Wide Range ◽  
Tangent Method ◽  
Classification Tool

The ASME Boiler and Pressure Vessel Code (code) provides guidelines for the classification of linear elastic stresses into primary, secondary, and peak stresses. Although these guidelines cover a wide range of pressure containing components, the guidelines are sometimes difficult to employ for three-dimensional components with complex geometry. This paper uses the mα-tangent method, an assessment of constraint in the component, based on limit load multiplier estimates as a stress classification tool. The method is applied to several practical pressure vessel components from simple to relatively complex geometric configurations. The results compare well with those obtained by conventional techniques, e.g., inelastic finite element analysis.

scholarly journals 3-D Finite Element Investigation of Flux Regulation Performance of a Novel Hybrid Excitation Brushless Claw-Pole Alternator

2012 ◽  
Vol 614-615 ◽  
pp. 1226-1229
Author(s):  
Dong Wei Qiao ◽  
Xiu He Wang ◽  
Chang Qing Zhu
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Analysis ◽  
Wide Range ◽  
Hybrid Excitation ◽  
Field Control ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Control Principle

In consideration of low power density of electric excitation claw-pole alternator (EECA) and some difficulties in magnetic field regulation of permanent magnet claw-pole alternator (PMCA), a novel hybrid excitation brushless claw-pole alternator (HEBCA) is proposed in this paper. Its structure and field control principle are described. Three dimensional finite element analysis is used to obtain the no-load magnetic field distributions and field control capability under different field currents. The result shows that the flux of the prototype machine can be adjusted over a wide range with a relatively low field current

Computational Design of a Reconfigurable Origami Space Structure Incorporating Shape Memory Alloy Thin Films

2012 ◽  
Author(s):  
Darren Hartl ◽  
Kathryn Lane ◽  
Richard Malak
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Three Dimensional ◽  
Computational Design ◽  
Passive Layer ◽  
Space Structure ◽  
Material System ◽  
Transient Effects ◽  
Element Analysis ◽  
Shell Elements

The subject of origami design is garnering increased attention from the science, mathematics, and engineering communities. However, relatively little research exists on understanding the behavioral aspects of the material system undergoing the folding operations. This work considers the design and analysis of a novel concept for a self-folding structure. It consists of an active, self-morphing laminate that includes thermally actuated shape memory alloy (SMA) layers and a compliant passive layer. Multiple layers allow folds in both the positive and negative directions relative to the laminate normal. The layers are configured to allow continuously variable folding operations based only on which regions are heated. For the purposes of demonstration, an example problem is considered whereby a thin structure is designed that can be stored in a flat sheet configuration and then morph using sets of folds toward two distinct shapes. We examine the effects of fold width, layer thicknesses, and activation power history on the geometric configurations that can be obtained. The design efforts are supported by a comprehensive and accurate three-dimensional constitutive model for SMAs implemented into a finite element analysis (FEA) framework. Shell elements and laminate theory are used to increase the computational efficiency of the analysis. Discussion of the complex effects of active folding in an SMA laminate sheet with in-plane homogeneity, including transient effects, are discussed.

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