A strain gradient strategy to quantifying longitudinal compression behavior in slender fibrous assembly structures

2021 ◽  
pp. 004051752110362
Author(s):  
Fengxin Sun ◽  
Yangyang Peng
Keyword(s):  
Strain Gradient ◽  
Structural Design ◽  
Compressive Load ◽  
Local Stress ◽  
Compression Modulus ◽  
Longitudinal Compression ◽  
Neutral Layer ◽  
Compression Behavior ◽  
Bending Property ◽  
Element Simulation

Slender fibrous assembled structures can easily buckle under longitudinal compressive load. The limitation in characterizing the longitudinal compression behavior poses a significant challenge to the mechanics optimization of such structures. To address this challenge, we use one-dimensional yarns as a model system, and the yarns are deformed in bending to form a strain gradient, from tension to compression, along the radial direction of the yarns. The compression modulus as a function of compression strain is calculated based on bi-moduli elastic theory. The evolution of the fiber arrangement and the position of the neutral layer in the yarn is interpreted along with the change of compression modulus. Also, the local stress distribution in the bent yarn was determined by finite element simulation, and it is remarked that the bending property of yarns is sensitive to the compression modulus. The present study offers insights on the modeling and simulation of fabrics and garments in drape and bending deformation. Results from such investigations can provide effective guidance for the mechanical and structural design of textiles and textile-based composites.

Numerical Analysis of Ship Wave Loads and Structure Strengthen Analysis on a Wind Power Installation Ship

2011 ◽  
Vol 90-93 ◽  
pp. 2521-2527
Author(s):  
Gang Qiang Li ◽  
Yan Yan Zhao ◽  
Yong He Xie
Keyword(s):  
Wind Power ◽  
Structural Design ◽  
Three Dimensional ◽  
Load Condition ◽  
Wave Loads ◽  
Element Simulation ◽  
Wind Power Installation ◽  
Wave Induced ◽  
Term Response

In a typical load condition of wind power equipment Installation ship, using the three-dimensional potential flow theory to prediction the long-term response of wave induced loads. then using the main load control parameters as a basis for the design wave selection, then application of DNV's SESTRA program make the wave-induced directly to the structure to finite element simulation. The results show that the hull structural design can meet the requirements.

scholarly journals Compression Properties and Its Prediction of Wood-Based Sandwich Panels with a Novel Taiji Honeycomb Core

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 886 ◽  
Author(s):  
Jingxin Hao ◽  
Xinfeng Wu ◽  
Gloria Oporto-Velasquez ◽  
Jingxin Wang ◽  
Gregory Dahle
Keyword(s):  
Compression Strength ◽  
Sandwich Structure ◽  
Mechanical Performance ◽  
Compression Modulus ◽  
Honeycomb Core ◽  
Compression Behavior ◽  
Measurement Systems ◽  
Compression Properties ◽  
Entire Structure ◽  
Core Thickness

The transverse compression property is one of most important aspects of the mechanical performance of a sandwich structure with a soft core. An experiment, analytical method and three digital strain measurement systems were applied to investigate the compression behavior and the failure mechanism for a wood-based sandwich structure with a novel Taiji honeycomb core. The results show that the structure of the Taiji honeycomb can improve dramatically on compression strength and modulus of composite compared to that of a traditional hexagonal one. There was no obvious deflection in the transverse direction detected by the three digital images before the buckling of the honeycomb occurred. An analytical equation between the key structure parameters and properties of the composite were applied to predict its threshold stresses and modulus. The properties of the core determine the strength of the entire structure, but the compression strength decreases slightly with an elevated core thickness, and its effect on the compression modulus can be neglected. Both the surface sheets and loading speed have little impact on the compression strength and modulus, respectively.

Static Characteristics of Micro Disc Magneto Electric Generator – Simulation and Experiment

2013 ◽  
Vol 365-366 ◽  
pp. 356-359
Author(s):  
Lin Du ◽  
Geng Chen Shi ◽  
Jing Jing Zhao
Keyword(s):  
Finite Element ◽  
Structural Design ◽  
Experimental Result ◽  
Static Characteristics ◽  
Element Analysis ◽  
Electric Generator ◽  
Design And Optimization ◽  
Element Simulation ◽  
Simulation And Experiment ◽  
3D Software

Maxwell 3D software of finite-element analysis in electromagnetic fields is used to model and simulate the micro disc magneto electric generator. Distribution characteristics of magnetic induction are required and theoretical analysis and calculation is presented. Error between the simulation result and experimental result is about 6% which verify the rationality and accuracy of finite-element simulation. It can be used to guide the structural design and optimization of this type of generator.

scholarly journals A Theoretical Method for Structural Design and Analysis of Crankshafts

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Sergio Baragetti
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Structural Design ◽  
Finite Element Modelling ◽  
Theoretical Method ◽  
Simple Theoretical Model ◽  
Element Simulation ◽  
Strain Behaviour ◽  
Numerical Finite Element ◽  
Theoretical Procedure

The crankshaft is the crucial mechanical component in many machines and engines and its fatigue assessment is often very time consuming and expensive. The machine designer usually needs a simple theoretical model that would allow choosing the best material and the dimensions of the component in a quick and reliable way. The numerical finite element simulation of crankshafts should follow the first step of theoretical dimensioning with the aim of evaluating the stress-strain behaviour at the notched area to verify the component against fatigue failure. The development of an intermediate theoretical model would prove effective to reduce the time needed to reach a second approximation design of the crankshaft. The aim of this paper is to give the designer a theoretical procedure that allows determining the strain and stress state for verification of crankshafts. The model was developed in the case of crankshafts with two connecting rods and validated by means of numerical finite element modelling and analysis.

scholarly journals Studies on the Residual Stress and Strain Gradients in Poly-SiGe Nanocantilevers

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Tesleem B Asafa
Keyword(s):  
Strain Gradient ◽  
Stress Gradient ◽  
Local Stress ◽  
Stress And Strain ◽  
Fast Method ◽  
Stress Evolution ◽  
Strain Gradients ◽  
Study Results ◽  
Evolution Study ◽  
Gradient Measurement

One of the fundamental structural requirements for Micro/Nano-ElectroMechanical (M/NEM) devices is low strain gradient. Measurement of strain gradients is time consuming, therefore finding a simple and fast method is necessary. In this paper, a comparative study of the strain gradients in poly-SiGe nanocantilevers measured experimentally and obtained using finite element modelling (FEM) approach is reported.  Arrays of nanocantilevers were fabricated from 100 nm thick poly-SiGe films via lithography. Then, strain gradients were calculated from the tip deflections and cantilevers’ lengths. In the modelling study, similar cantilevers were modelled with COMSOL Multiphysics as superposition of smaller layers in which each layer sustained local stress obtained from stress evolution study. Results showed that the average strain gradients obtained from the experimental and FEM studies differ by ~5% and ~6% for film A and B, respectively with standard deviations lying between ±0.004 and ±0.009/µm. While this study established that stress gradient is responsible for the calculated strain gradient, it also emphasises that both parameters are proportional. Key words: Poly-SiGe, Strain gradient, FEM, COMSOL.

scholarly journals Thin-coating contact mechanics with adhesion

2006 ◽  
Vol 21 (10) ◽  
pp. 2660-2668 ◽  
Author(s):  
E.D. Reedy
Keyword(s):  
Finite Element ◽  
Contact Mechanics ◽  
Contact Area ◽  
Elementary Theory ◽  
Compressive Load ◽  
Square Root ◽  
Thin Coating ◽  
Element Analysis ◽  
Linear Elastic ◽  
Element Simulation

An elementary theory for a rigid spherical indenter contacting a thin, linear elastic coating that is bonded to a rigid substrate was developed. This theory predicts that contact area varies as the square root of the compressive load in contrast to Hertz theory where contact area varies as the two-thirds power of the compressive load. Finite element analysis confirmed an approximate square root dependence of contact area on compressive load when the coating thickness-to-indenter radius ratio is less than 0.1 and when the coating Poisson’s ratio is less than 0.45. Thin-coating contact mechanics theories that use either the Derjaguin-Muller-Toporov (DMT) approximation or the Johnson-Kendall-Roberts (JKR) approximation were also developed. In addition, a finite element simulation capability that includes adhesion was developed and verified. Illustrative finite element simulations that include adhesion were then performed for a thin elastic coating (rigid indenter/substrate). Results were compared with the thin-coating contact theories and the transition from DMT-like to JKR-like response was examined.

Bio-Inspired Fast Actuation by Mechanical Instability of Thermoresponding Hydrogel Structures

2016 ◽  
Vol 83 (7) ◽  
Author(s):  
Xuxu Yang ◽  
Guorui Li ◽  
Tingyu Cheng ◽  
Qian Zhao ◽  
Chunxin Ma ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Finite Element ◽  
Control System ◽  
Structural Design ◽  
Multilayered Structure ◽  
Mechanical Instability ◽  
Triggering Mechanism ◽  
Element Simulation ◽  
Ca Alginate ◽  
Poly Acrylamide

Inspired by natural plants, thermoresponding hydrogel (TRH) structures have been designed to trigger mechanical instability with fast actuation. Tough Ca-alginate/poly(N-isopropylacrylamide) (PNIPAM) hydrogel has been synthesized by the hybrid of physically cross-linked alginate and covalently cross-linked PNIPAM. The tough Ca-alginate/PNIPAM hydrogel exhibits 30 kPa of elastic modulus, 280 J/m2 of fracture energies, and fivefold of uniaxial stretch. A multilayered structure made of (Ca-alginate/PNIPAM)/(Ca-alginate/poly (acrylamide)) hydrogels demonstrate fast actuation induced by mechanical instability. A finite-element simulation model is developed to investigate the deformation and to guide the structural design of the hydrogels. The instability-triggering mechanism can enhance the actuation performances of hydrogel structures in applications, such as drug delivery, microfluid control system, and soft biomimetic robotics.

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