Conventional and Auxetic SMA Cellular Structures

Aerospace ◽  
2005 ◽  
Author(s):  
Mohd R. Hassan ◽  
F. Scarpa ◽  
N. A. Mohammed ◽  
Y. Ancrenaz
Keyword(s):  
Room Temperature ◽  
Strain Curve ◽  
Tensile Tests ◽  
Core Material ◽  
Stress Strain Curve ◽  
Beam Elements ◽  
Commercial Code ◽  
Unit Cells ◽  
Novel Concept ◽  
Good Agreement

This work illustrates the manufacturing and tensile testing of a novel concept of honeycomb structures with hexagonal and auxetic (negative Poisson’s ratio) topology, made of shape memory alloy (SMA) core material. The honeycombs are manufactured using Nitinol ribbons having 6.40 mm of width and 0.2 mm of thickness. The ribbons were inserted in a special dye using cyanoacrilate to bond the longitudinal strips of the unit cells. The ribbons were subjected to tensile test at room temperature (martensite finish) and austenite finish temperature. Tensile tests at room temperature were performed on the honeycomb. The stress-strain curve obtained from the test on a single ribbon at room temperature was then used to develop nonlinear Finite Element beam elements using a commercial code. The beam elements were then used to model the honeycomb samples under tensile loading. Good agreement is observed between numerical nonlinear simulations and the experimental results.

scholarly journals A space structural mechanics model of silicene

2020 ◽  
Vol 234 (1-2) ◽  
pp. 3-10
Author(s):  
Mohsen Motamedi
Keyword(s):  
Natural Frequencies ◽  
Strain Curve ◽  
Structural Mechanics ◽  
Dynamics Simulation ◽  
Mode Shapes ◽  
Two Dimensional ◽  
Stress Strain Curve ◽  
Beam Elements ◽  
Mechanics Model ◽  
Good Agreement

The two-dimensional nanostructures such as graphene, silicene, germanene, and stanene have attracted a lot of attention in recent years. Many studies have been done on graphene, but other two-dimensional structures have not yet been studied extensively. In this work, a molecular dynamics simulation of silicene was done and stress–strain curve of silicene was obtained. Then, the mechanical properties of silicene were investigated using the proposed structural molecular mechanics method. First, using the relations governing the force field and the Lifson–Wershel potential function and structural mechanics relations, the coefficients for the BEAM elements was determined, and a structural mechanics model for silicene was proposed. Then, a silicene sheet with 65 Å × 65 Å was modeled, and Young’s modulus of silicene was obtained. In addition, the natural frequencies and mode shapes of silicene were calculated using finite element method. The results are in good agreement with reports by other papers.

scholarly journals A study of the Cu0.95Al0.05 alloy: stress-strain curve and microstructure

2018 ◽  
Vol 20 (2) ◽  
Author(s):  
Emilio Medrano ◽  
Mauro Quiroga ◽  
Felipe A. Reyes
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Strain Curve ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Metal Alloys ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Electrolytic Copper ◽  
Mechanical Traction

After fabricating five metallographic specimens of the Cu0.95Al0.05 alloy from electrolytic copper and aluminum, these ones were both microstructurally characterized by using a metallographic optical microscope at room temperature and subjected to mechanical traction in order to chart the stress-strain curve. From the characterization, it has been found out that the Cu0.95Al0.05 microstructure is composed of a single phase, and from the tensile tests, it has been obtained its rupture point, 249.361 MPa. The obtained results were explained in the framework of the theory of metals and metal alloys.

Consititutive Modeling for Auto-Body Steel Sheet Incorporating Strain Rate and Temperature

2011 ◽  
Vol 189-193 ◽  
pp. 2925-2929
Author(s):  
Wen Ping Wang ◽  
Min Wan ◽  
Hai Bo Wang ◽  
Xiang Dong Wu ◽  
Ke Shan Diao
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Steel Sheet ◽  
Strain Curve ◽  
Tensile Tests ◽  
Experimental Result ◽  
Stress Strain Curve ◽  
User Subroutine ◽  
Auto Body ◽  
Good Agreement

Uniaxile tensile tests of auto-body steel sheet were performed at strain rate of 10-4 to 101s-1 and temperature of room temperature to 180°C. Strain rate and temperature sensitivity of flow stress were analyzed. It is found that the stress-strain curve is obviously heavily weighted on the temperature and strain rate. A new constitutive model was constructed and implemented into Abaqus/Explicit commercial software using user subroutine VUMAT. Verification of constitutive model shows that it has good agreement with experimental result.

Characterisation of Elastoplastic Behaviour Using Spherical Indentation

2006 ◽  
Vol 514-516 ◽  
pp. 744-748
Author(s):  
António Castanhola Batista ◽  
José P. Marinheiro ◽  
Joao P. Nobre ◽  
A. Morão Dias
Keyword(s):  
Inverse Method ◽  
Indentation Test ◽  
Strain Curve ◽  
Tensile Tests ◽  
Spherical Indentation ◽  
Stress Strain Curve ◽  
Hardening Law ◽  
Behaviour Study ◽  
Behaviour Law ◽  
Good Agreement

An inverse method for the characterisation of the elastoplastic behaviour of materials has been studied. The method is based on spherical indentation test data and numerical analysis of the indentation process, enabling to find a characteristic stress-strain curve. This method will be appropriate for elastoplastic behaviour study, mainly on surface hardened materials, when the standard methods cannot be applied. In this work, the method was applied to annealed and quenched steels, with homogeneous properties over the cross section. The obtained results are in good agreement with those obtained from the standard tensile tests. However, if the material does not follow a linear hardening law, the elastoplastic characteristics determined by the inverse method will depend on the indentation depth. For these cases a method for the evaluation of the actual behaviour law has been improved.

The Behavior of Raw Rubber When Stretched Isothermally

1938 ◽  
Vol 11 (4) ◽  
pp. 647-652 ◽  
Author(s):  
H. Hintenberger ◽  
W. Neumann
Keyword(s):  
Room Temperature ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Steep Ascent ◽  
Flow Effect ◽  
Vulcanized Rubber ◽  
Flow Phenomena ◽  
Entropy Effect ◽  
The Subject

Abstract The S-shaped form of the stress-strain curve of rubber is today explained in a quite satisfactory way. In the first part of the curve, i. e., the gradual ascent, work must be expended because of the van der Waals forces of attraction of the molecules; in the second part, i. e., the steep ascent, the elasticity is chiefly an entropy effect, which is finally exceeded by crystallization phenomena. The phenomenon of crystallization itself has been the subject of extensive investigations, but in most cases vulcanized rubber has been employed, and because of the various accelerators and fillers which the rubber has contained, the products have been rather ill-defined. It is evident that the phenomena involved in crystallization would be much more clearly defined if the substance under investigation were to be in a higher state of purity. If experiments are carried out with raw rubber, a flow effect is added to the various other phenomena. As a result of this flow effect, Rosbaud and Schmidt, and Hauser and Rosbaud as well, found that the stress-strain curve depends on the rate of elongation at very low extensions, with a greater stiffness at high rates of elongation. As found recently by Kirsch, there is no evidence of any flow phenomena in vulcanized rubber at room temperature. Most investigations have been so carried out that the stress has been measured at a definite elongation. It was therefore of interest to determine the elongation at constant stress, and the changes in this relation with time and with temperature, of various types of raw rubber.

Compressive Plasticity of Zr-Based Bulk Metallic Glass at Low Temperature

2012 ◽  
Vol 443-444 ◽  
pp. 583-586
Author(s):  
Ya Juan Sun ◽  
Ri Ga Wu ◽  
Hong Jing Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Low Temperatures ◽  
Room Temperature ◽  
Shear Bands ◽  
Strain Curve ◽  
Testing Temperature ◽  
Stress Strain Curve

The mechanical properties of a new Zr-based bulk metallic glass at low temperatures were investigated. The results indicate that the fracture strength increases significantly (4.9%) and the global plasticity increases somewhat when testing temperature is lowered to 123K. The stress-strain curve of the sample deformed exhibits more serrations and smaller stress drop due to formation of more shear bands at low temperature than at room temperature.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

scholarly journals Effects of layer shift and yarn path variability on mechanical properties of a twill weave composite

2016 ◽  
Vol 51 (7) ◽  
pp. 913-925 ◽  
Author(s):  
MY Matveev ◽  
AC Long ◽  
LP Brown ◽  
IA Jones
Keyword(s):  
Numerical Analysis ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
Damage Propagation ◽  
Macro Scale ◽  
Twill Weave ◽  
Modulus Reduction ◽  
Good Agreement

Experimental and numerical analyses of a woven composite were performed in order to assess the effect of yarn path and layer shift variability on properties of the composite. Analysis of the geometry of a 12 K carbon fibre 2 × 2 twill weave at the meso- and macro-scales showed the prevalence of the yarn path variations at the macro-scale over the meso-scale variations. Numerical analysis of yarn path variability showed that it is responsible for a Young’s modulus reduction of 0.5% and CoV of 1% which makes this type of variability in the selected reinforcement almost insignificant for an elastic analysis. Finite element analysis of damage propagation in laminates with layer shift showed good agreement with the experiments. Both numerical analysis and experiments showed that layer shift has a strong effect on the shape of the stress–strain curve. In particular, laminates with no layer shift tend to exhibit a kink in the stress–strain curve which was attributed solely to the layer configuration.

Fabrication of Faucet Using Hydroforming and Bending Processing

2014 ◽  
Vol 626 ◽  
pp. 293-300 ◽  
Author(s):  
Hui Wen Hu ◽  
Ting Yu Chen ◽  
Sheng Yuan Wang ◽  
Tien Yo Ho
Keyword(s):  
Internal Pressure ◽  
Piecewise Linear ◽  
Strain Curve ◽  
Element Model ◽  
Stress Strain Curve ◽  
Forming Process ◽  
Commercial Code ◽  
Simulation And Experiment ◽  
Profile Dimension ◽  
Walled Cylinder

This research aims at the development of faucet using the techniques of hydroforming and bending. In this study, a tube made from stainless steel SUS 304 is used. Finite element model, including tube, dies and punches, are established using a commercial code LS-DYNA. Tensile test is used to obtain the material properties especially in true stress-strain curve. Piecewise linear plasticity model is used to simulate the plastic deformation of material during the forming process. The initial internal pressure is designed by using the theory of thick-walled cylinder subjecting to internal pressure only. Simulation is first used to find the optimal loading conditions for hydroforming and bending forming. Experiment is then performed to fabricate the prototype of faucets using the simulated loading parameters. The results show that good correlation of the distributed thickness and profile dimension between simulation and experiment are obtained.

RESEARCH OF MAXILLARY IMPACTED CANINE IN ORTHODONTIC TREATMENT BASED ON NANOINDENTATION EXPERIMENTS

2017 ◽  
Vol 17 (07) ◽  
pp. 1740029
Author(s):  
BIN WU ◽  
YUNYUN ZHU ◽  
RUXIN LU ◽  
BIN YAN ◽  
YIPENG FU ◽  
...  
Keyword(s):  
Orthodontic Treatment ◽  
Strain Curve ◽  
Root Apex ◽  
Stress Strain Curve ◽  
Third Order ◽  
Stress Variation ◽  
The Third ◽  
Ogden Model ◽  
Impacted Canine ◽  
Good Agreement

This study selected the maxillary labial impacted canine as the research object to build the model of periodontal ligament (PDL) and simulate the process of orthodontic treatment. This paper obtained stress–strain curve by calculating and analyzing the data of nanoindentation experiments. The parameters were identified through curve fittings by ABAQUS. The fitting results show that the third-order Ogden model is in good agreement with the experimental data which demonstrate that the third-order Ogden model is able to reflect the material properties of the PDL. In this paper, orthodontic process of the maxillary labial impacted canine was simulated. The results show that inside and outside surfaces of PDL all have stress variation, the stress on the root apex and dental cervix of PDL is relatively large, the maximum appears at dental cervix and the minimum appears close to tooth impedance center.

Sign in / Sign up

Export Citation Format

Share Document