Stress-strain curve of paper revisited

2012 ◽  
Vol 27 (2) ◽  
pp. 318-328 ◽  
Author(s):  
Svetlana Borodulina ◽  
Artem Kulachenko ◽  
Mikael Nygårds ◽  
Sylvain Galland
Keyword(s):  
Three Dimensional ◽  
Strain Curve ◽  
Failure Behavior ◽  
Three Dimensional Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Fiber Network ◽  
Bonding Parameters ◽  
Particle Level ◽  
The Impact

Abstract We have investigated a relation between micromechanical processes and the stress-strain curve of a dry fiber network during tensile loading. By using a detailed particle-level simulation tool we investigate, among other things, the impact of “non-traditional” bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds. This is probably the first three-dimensional model which is capable of simulating the fracture process of paper accounting for nonlinearities at the fiber level and bond failures. The failure behavior of the network considered in the study could be changed significantly by relatively small changes in bond strength, as compared to the scatter in bonding data found in the literature. We have identified that compliance of the bonding regions has a significant impact on network strength. By comparing networks with weak and strong bonds, we concluded that large local strains are the precursors of bond failures and not the other way around.

scholarly journals Study on the Physical Properties and Joint Evolution Characteristics of Three-Dimensional Reconstructed Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yongning Wu ◽  
Zhe Zhang ◽  
Xinzhe Wang ◽  
Peiyang Zhu ◽  
Xin Yang ◽  
...  
Keyword(s):  
Coal Sample ◽  
Three Dimensional ◽  
Monitoring Program ◽  
Strain Curve ◽  
Joint Surface ◽  
Three Dimensional Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Joint Monitoring ◽  
Joint Evolution

There are various complex joints (fissures), laminae, and other soft structural surfaces in the roadway enclosure, and the existence of these soft structural surfaces seriously affects the stability of the roadway enclosure. In order to study the mechanical properties of the coal body and the development of joints during coal fracture, this paper establishes a three-dimensional model of the fracture structure of the coal body based on CT scanning and three-dimensional reconstruction technology. On this basis, a 3D numerical model of the equivalent nodal coal body is constructed, uniaxial compression simulation analysis is performed, and the joint evolution development law of the coal sample is studied by the built-in joint monitoring program of PFC3D. The results show that the larger the effective joint area and larger the joint size inside the coal sample, the smaller the compressive strength of the coal sample. The increase of joint size and joint surface area increased the ductility and stress-strain curve multipeak phenomenon of the coal sample to some extent. During the rupture of the coal sample, the changes of each phase of the statistical curve of joint number and the phases of the stress-strain curve of the coal sample are compatible.

Dynamic Stress-Strain Relations for Annealed 2S Aluminum Under Compression Impact

1953 ◽  
Vol 20 (4) ◽  
pp. 523-529
Author(s):  
J. E. Johnson ◽  
D. S. Wood ◽  
D. S. Clark
Keyword(s):  
Dynamic Stress ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Impact Stress ◽  
Stress Strain Relation ◽  
Final Strain ◽  
Dynamic Relations ◽  
Single Stress ◽  
The Impact

Abstract This paper presents the results of an experimental study of the stress-strain relation of annealed 2S aluminum when subjected to compression impact. Two methods of securing a dynamic stress-strain curve are considered, namely, from the measurement of impact stress as a function of maximum plastic strain, and impact stress as a function of the impact velocity. The dynamic stress-strain curves obtained by these methods lie considerably above the static curve. The elevation in stress of the dynamic relations above the static relation increases progressively from zero at the elastic limit to about 20 per cent at a strain of 4.5 per cent. However, the two dynamic relations are not coincident which indicates that the behavior of the material cannot be described by a single stress-strain curve for all impact velocities. A family of stress-strain curves which differ slightly from each other and which depend upon the final strain is postulated in order to correlate both sets of data adequately.

An Experimental Investigation of Elastic-Plastic Pulse Propagation in Aluminum Rods

1967 ◽  
Vol 34 (1) ◽  
pp. 91-99 ◽  
Author(s):  
S. R. Bodner ◽  
R. J. Clifton
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Static Stress ◽  
Stress Strain Curve ◽  
Proportional Limit ◽  
Stress Strain ◽  
Elastic Plastic ◽  
Time Profiles ◽  
The Impact

Experiments are reported involving elastic-plastic pulses due to explosive loading at one end of long, annealed, commercially pure, aluminum rods at room temperature and at elevated temperatures up to 750 deg F. The stress waves were detected by a condenser microphone at the far end of the rod and, in some cases, by strain gages at a cross section distant from the impact end. The essential features of the recorded velocity-time profiles and strain-time profiles are found to be in agreement with the predictions of rate independent elastic-plastic theory which takes a Bauschinger effect into account. At room temperature, the reference dynamic stress-strain curve does not differ appreciably from the quasi-static stress-strain curve whereas at elevated temperatures there appears to be a marked difference between the dynamic and quasi-static stress-strain curves. The experiments also serve to determine the dynamic proportional limit which is found to be fairly insensitive to temperature. Since the maximum plastic strains are small at cross sections remote from the impact end, the measurements, and consequently the conclusions, are limited to small strains beyond the proportional limit.

Reliability Analysis of LCF Life for a Turbine Disk

2010 ◽  
Vol 146-147 ◽  
pp. 1379-1385
Author(s):  
Yang Gao ◽  
Chang Jun Yang ◽  
Kai Lin ◽  
Qing Gao
Keyword(s):  
Reliability Analysis ◽  
Low Cycle Fatigue ◽  
Three Dimensional ◽  
Strain Curve ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Turbine Disk ◽  
Fatigue Reliability ◽  
Three Dimensional Model ◽  
Stress Strain

Cyclic stress-strain curve and cyclic strain-life curve appear distinct scatters, and the scatter of fatigue life increases with reducing of the strain levels. A methodology for reliability simulation of low cycle fatigue (LCF) life for turbine disk structures is developed in this paper. First, probabilistic cyclic stress-strain model and linear heteroscedastic probabilistic cyclic strain-life model are founded based on the fatigue test data. Second, three dimensional model of a turbine disk is built, and the fatigue reliability analysis of this turbine disk is implemented in probabilistic design module (PDS) of ANSYS by the combination of response surface method (RSM) and Monte Carlo simulation (MCS). The predicted life with reliability 0.9987 is well consistent with the technology life obtained from disks LCF tests by scatter factors method.

The Free Plastic Compression of Pure Metals

1970 ◽  
Vol 37 (4) ◽  
pp. 1121-1126
Author(s):  
V. S. Shankhla ◽  
R. F. Scrutton
Keyword(s):  
Strain Rate ◽  
Dynamic Compression ◽  
Strain Curve ◽  
Initial Strain Rate ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Plastic Properties ◽  
Pure Lead ◽  
Pure Metals ◽  
The Impact

The dynamic compression of a billet by the impact of a falling weight is analyzed with reference to the general plastic properties of pure metals. Theoretical results are compared with the results of published experimental data for pure lead. It is shown that, for lead, the form of the stress-strain curve is little influenced by changes in strain rate during deformation. The strain-hardening coefficient is however found to be strongly influenced by the temperature changes associated with the adiabatic deformation. The position of the maximum in the stress-strain curve is sensitive to the value of the initial strain rate. A method is suggested whereby isothermal stress-strain relationships may be extended to include the effects of adiabatic thermal softening.

Numerical Study on the Mechanical Behavior of Aluminum Foam Material Using CT Image

2009 ◽  
Vol 79-82 ◽  
pp. 1297-1300 ◽  
Author(s):  
Hyup Jae Chung ◽  
Kyong Yop Rhee ◽  
Beom Suck Han ◽  
Yong Mun Ryu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Foam ◽  
Three Dimensional ◽  
Strain Curve ◽  
Foam Material ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
X Ray

In this study, finite element analysis was made to predict the tensile and compressive behaviors of aluminum foam material. The predicted tensile and compressive behaviors were compared with those determined from the tensile and compressive tests. X-ray imaging technique was used to determine internal structure of aluminum foam material. That is, X-ray computed tomography (CT) was used to model the porosities of the material. Three-dimensional finite element modeling was made by stacking two-dimensional tomography of aluminum foam material determined from CT images. The stackings of CT images were processed by three-dimensional modeling program. The results showed that the tensile stress-strain curve predicted from the finite element analysis was similar to that determined by the experiment. The simulated compressive stress-strain curve also showed similar tendency with that of experiment up to about 0.4 strain but exhibited a different behavior from the experimental one after 0.4 strain. The discrepancy of compressive stress-strain curves in a high strain range was associated with the contact of aluminum foam walls broken by the large deformation.

A new test for determining the mechanical and fracture behavior of materials in sheet-bulk metal forming

2015 ◽  
Vol 231 (8) ◽  
pp. 693-703 ◽  
Author(s):  
CMA Silva ◽  
MB Silva ◽  
LM Alves ◽  
PAF Martins
Keyword(s):  
Fracture Toughness ◽  
Metal Forming ◽  
Three Dimensional ◽  
Strain Curve ◽  
Shear Zones ◽  
Shear Stresses ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Bulk Metal ◽  
Bulk Metal Forming

This paper presents a new experimental test for determining the stress–strain curve and the fracture toughness of sheets to be used in sheet-bulk metal forming (SBMF) applications. The test is based on the utilization of double-notched specimens loaded in shear and combines the plane stress loading conditions of sheet metal forming with the three-dimensional plastic flow conditions of bulk metal forming, which are commonly found in SBMF processes. The methodology to obtain the stress–strain curve involves calculation of the shear stresses and strains along the two symmetric plastic shear zones of the test specimens up to point where cracks start to propagate along the ligaments that connect each pair of opposite notches. The determination of fracture toughness involves characterization of the evolution of load with displacement for a number of test cases performed with specimens having different ligaments between the two symmetric opposite notches. The work is performed on aluminium alloy EN AW 5754 H111 sheets with 5 mm thickness and the results obtained by means of the new proposed test are compared against those from conventional mechanical and fracture characterization tests.

scholarly journals THERMO-MECHANICAL PROPERTIES OF NITI CLOSED COIL SPRINGS – FORCE DEGRADATION AND FORCE REGENERATION OVER TIME, VISCOUS PROPERTIES

2013 ◽  
Vol 56 (2) ◽  
pp. 41-46 ◽  
Author(s):  
Aleš Bezrouk ◽  
Libor Balský ◽  
Martin Smutný ◽  
Tomáš Nosek ◽  
Jiří Záhora ◽  
...  
Keyword(s):  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Large Hysteresis ◽  
Plateau Area ◽  
Stress Cycling ◽  
The Difference ◽  
Mechanically Stabilized ◽  
The Impact ◽  
Over Time

Introduction: The aim of this study was to find out the impact of degradation and regeneration of force over time at NiTi springs on the value and course of the final acting force and to verify the possibility of using these phenomena for a directed transition to the reverse plateau and its maintaining. Methods: Static and cyclic mechanical loadings were performed. At first unused springs were tested. Afterwards the springs were mechanically stabilized by stress cycling and finally tested again. The difference in shape of the working curves was assessed. For simulation and description of the force degradation the modified Voight model was used. Results: New springs, mainly those with large hysteresis, showed a significant stress-strain curve movement and shape changes during the cycling. The effect of the stress-strain curve course change disappeared fully in the stabilized springs. Multiple loading led to an overall decrease of force value during the measurement. The effect of force degradation and regeneration over time by simple static loading varies in the range of percentage of the nominal force in the plateau area. The transition between stress-strain curve phases caused by the degradation or regeneration of the force wasn’t observed in case of mechanically stabilized springs. Conclusions: Springs should be mechanically stabilized before their application. The degree of force degradation over time is insignificant for mechanically stabilized springs. Degradation or regeneration of force over time, mechanical stabilization or micromovements in the mouth don’t cause any transition between individual stress-strain curve phases.

A Three-Dimensional Atomic-Scale Finite Element Model for a Copper Nano Thin Film Subject to a Uniaxial Tension

2012 ◽  
Vol 579 ◽  
pp. 453-463
Author(s):  
Jinn Tong Chiu ◽  
Yeou Yih Lin ◽  
Ship Peng Lo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain Rate ◽  
Three Dimensional ◽  
Strain Curve ◽  
Element Model ◽  
Tension Test ◽  
Atomic Scale ◽  
Stress Strain Curve ◽  
Stress Strain

A three-dimensional atomic-scale finite element model was developed in this paper for simulation of a nano-scale uniaxial tension. First, the Morse’s potential function was used to simulate the forces acting among particles. Furthermore, a non-linear spring and dashpot element with a lumped mass was used to establish an atomic model. The elongation of the spring at fracture was used to simulate the radius of fracture of the atomic link. This method was applied to investigate the proportional tension test of an idealized FCC single crystal copper film along the x direction. The study includes the stress-strain curve, the effect of five categories of atomic distances on the stress-strain curve; and the effect of strain-rate on the stress-strain curve. The results showed that (1)the simulated maximum stress for copper is very close to 30.0GPa, which is also the value of maximum equivalent stress obtained by Lin and Hwang [6], verifying the validity of the calculation of this paper. In the tension test of copper, necking develops gradually and eventually leads to fracture. The simulated deformed material element during each stage of deformation was similar to that simulated by Komanduri et al.[2](2)the influence of =6.2608 on the five categories of atomic distance considered was limited and it may be neglected to save computation time,(3)when the strain-rate was large, the resistance to deformation was also large, leading to an increase in the yield stress and fracture stress.

Understanding extensibility of paper: Role of fiber elongation and fiber bonding

TAPPI Journal ◽  
2020 ◽  
Vol 19 (3) ◽  
pp. 125-135
Author(s):  
JARMO KOUKO ◽  
TUOMAS TURPEINEN ◽  
ARTEM KULACHENKO ◽  
ULRICH HIRN ◽  
ELIAS RETULAINEN
Keyword(s):  
Strain Curve ◽  
Tensile Tests ◽  
Pulp Fibers ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Fiber Network ◽  
Fiber Networks ◽  
Strain Behavior ◽  
Softwood Kraft Pulp ◽  
Random Fiber Networks

The tensile tests of individual bleached softwood kraft pulp fibers and sheets, as well as the micro-mechanical simulation of the fiber network, suggest that only a part of the elongation potential of individual fibers is utilized in the elongation of the sheet. The stress-strain curves of two actual individual pulp fibers and one mimicked classic stress-strain behavior of fiber were applied to a micromechanical simulation of random fiber networks. Both the experimental results and the micromechanical simulations indicated that fiber bonding has an important role not only in determining the strength but also the elongation of fiber networks. Additionally, the results indicate that the shape of the stress-strain curve of individual pulp fibers may have a significant influence on the shape of the stress-strain curve of a paper sheet. A large increase in elongation and strength of paper can be reached only by strength-ening fiber-fiber bonding, as demonstrated by the experimental handsheets containing starch and cellulose microfi-brils and by the micromechanical simulations. The key conclusion related to this investigation was that simulated uniform inter-fiber bond strength does not influence the shape of the stress-strain curve of the fiber network until the bonds fail, whereas the number of bonds has an influence on the activation of the fiber network and on the shape of the whole stress-strain curve.

Sign in / Sign up

Export Citation Format

Share Document