scholarly journals On the behavior of slackline webbings under dynamic loads and the simulation of leash falls

2018 ◽  
Vol 233 (1) ◽  
pp. 75-85
Author(s):  
Panos J Athanasiadis
Keyword(s):  
Standardized Test ◽  
Strain Curve ◽  
Effective Modulus ◽  
Dynamic Loads ◽  
Elastic Response ◽  
Elastic Behavior ◽  
Stress Strain ◽  
Different Types ◽  
The Impact ◽  
Minimal Research

Slackline is a new and rapidly expanding sport, which has had minimal research published on it in terms of sport physics and engineering. Slackline dynamics strongly depend upon the elastic response of used webbing, typically made of polyester or nylon. Depending on the stress and strain rates applied, polymers are known to exhibit a visco-elastic behavior characterized by hysteresis effects. Through a series of carefully executed experiments, this study examined the behavior of slackline webbing under dynamic loads to determine the departures from the respective static response (stress–strain curves). Such knowledge is fundamental for the accurate simulation of slackline dynamics, so as to predict peak forces and aid safe rigging. The results demonstrate that the effective modulus during leash falls was significantly higher than the slope of the respective stress–strain curve, indicating a stiffer response. Also, the effective modulus increased with the applied pretension. Using the moduli determined experimentally for the rigged slacklines with different types of webbing, the respective leash falls were simulated numerically with high accuracy. A standardized test is proposed, to be adopted by the International Slackline Association and slackline webbing manufacturers, is proposed in order to provide key information on the response of each webbing available in the market under typical dynamic loads, similar to the “impact force” test designed for dynamic ropes by the International Climbing and Mountaineering Federation.

scholarly journals Black rubber and the non-linear elastic response of scale invariant solids

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Matteo Baggioli ◽  
Víctor Cáncer Castillo ◽  
Oriol Pujolàs
Keyword(s):  
Strain Curve ◽  
Effective Field ◽  
Elastic Response ◽  
Elastic Behaviour ◽  
Scale Invariant ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Hyper Elastic ◽  
Simple Class ◽  
Nonlinear Elastic

Abstract We discuss the nonlinear elastic response in scale invariant solids. Following previous work, we split the analysis into two basic options: according to whether scale invariance (SI) is a manifest or a spontaneously broken symmetry. In the latter case, one can employ effective field theory methods, whereas in the former we use holographic methods. We focus on a simple class of holographic models that exhibit elastic behaviour, and obtain their nonlinear stress-strain curves as well as an estimate of the elasticity bounds — the maximum possible deformation in the elastic (reversible) regime. The bounds differ substantially in the manifest or spontaneously broken SI cases, even when the same stress- strain curve is assumed in both cases. Additionally, the hyper-elastic subset of models (that allow for large deformations) is found to have stress-strain curves akin to natural rubber. The holographic instances in this category, which we dub black rubber, display richer stress- strain curves — with two different power-law regimes at different magnitudes of the strain.

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 Stress-strain curve of concretes with recycled concrete aggregates: analysis of the NBR 8522 methodology

2017 ◽  
Vol 10 (3) ◽  
pp. 547-567 ◽  
Author(s):  
D. A. GUJEL ◽  
C. S. KAZMIERCZAK ◽  
J. R. MASUERO
Keyword(s):  
Test Procedure ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Load Test ◽  
Recycled Aggregates ◽  
Elastic Behavior ◽  
It Use ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Brazilian Standard

ABSTRACT This work analyses the methodology "A" (item A.4) employed by the Brazilian Standard ABNT 8522 (ABNT, 2008) for determining the stress-strain behavior of cylindrical specimens of concrete, presenting considerations about possible enhancements aiming it use for concretes with recycled aggregates with automatic test equipment. The methodology specified by the Brazilian Standard presents methodological issues that brings distortions in obtaining the stress-strain curve, as the use of a very limited number of sampling points and by inducing micro cracks and fluency in the elastic behavior of the material due to the use of steady stress levels in the test. The use of a base stress of 0.5 MPa is too low for modern high load test machines designed do high strength concrete test. The work presents a discussion over these subjects, and a proposal of a modified test procedure to avoid such situations.

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.

The Studies of Rock Damage Softening Statistical Constitutive Model under True Triaxial Stress State

2014 ◽  
Vol 580-583 ◽  
pp. 312-315
Author(s):  
Hui Mei Zhang ◽  
Xiang Miao Xie ◽  
Geng She Yang
Keyword(s):  
Constitutive Model ◽  
Strain Curve ◽  
Stress Path ◽  
Complex Stress ◽  
Model Parameters ◽  
Stress Strain ◽  
Deformation And Failure ◽  
True Triaxial ◽  
Complex Stress Path ◽  
The Impact

From the feature of rock micro-unit failure obeys Poisson random distribution, the damage softening statistical constitutive of was established under true triaxial confinement based on D-P criterion, so the impact of the intermediate principal stress on rock deformation and failure was considered in theory, and the actual engineering rock complex stress path evolution was reflected more realistically. Furthermore, according to the geometrical conditions of stress-strain relationship, the theoretical relationship between constitutive model parameters and the stress-strain curve characteristic parameters during the process of rock softening and deforming, which enhance the adaptability of the model. Finally, the rationality of the model verified by the measured data.

A constitutive model of concrete confined by steel reinforcements and steel jackets

2005 ◽  
Vol 32 (1) ◽  
pp. 279-288 ◽  
Author(s):  
Y-F Li ◽  
S-H Chen ◽  
K-C Chang ◽  
K-Y Liu
Keyword(s):  
Constitutive Model ◽  
Concrete Strength ◽  
Strain Curve ◽  
Steel Reinforcement ◽  
Confined Concrete ◽  
Stress Strain ◽  
Steel Jacket ◽  
Proposed Model ◽  
Concrete Cylinders ◽  
Different Types

In this paper, a total of 60 concrete cylinders 30 cm in diameter and 60 cm in length confined by steel jackets of different thicknesses and different types of lateral steel reinforcements are tested to obtain the stress–strain curves of the cylinders. A constitutive model is proposed to describe the behavior of concrete confined by steel reinforcement, steel jackets, and both steel reinforcement and steel jackets used to retrofit and strengthen reinforced concrete structures. The confined concrete stress–strain curve of the proposed model is divided into two regions: the curve in the first region is approximated using a second-order polynomial equation, and that in the second region using an nth-order power-law equation, where n is a function of the unconfined concrete strength and the lateral confining stress. The results of the experiments show that different types of lateral steel reinforcement contribute greatly to the compressive strength of concrete cylinders confined by the reinforcement. Comparing the stress–strain curves of the uniaxial test with that from the proposed model, we conclude that the proposed model for concrete confined by a steel jacket and lateral steel reinforcement can predict the experimental results very well.Key words: constitutive model, steel jacket, confined concrete.

scholarly journals Linear and nonlinear modulus surfaces in stress space, from stress-strain measurements on Berea sandstone

2003 ◽  
Vol 10 (6) ◽  
pp. 589-597 ◽  
Author(s):  
M. Boudjema ◽  
I. B. Santos ◽  
K. R. McCall ◽  
R. A. Guyer ◽  
G. N. Boitnott
Keyword(s):  
Hysteretic Behavior ◽  
Elastic Response ◽  
Elastic Behavior ◽  
Dynamic Shear Modulus ◽  
Number Density ◽  
Berea Sandstone ◽  
Stress Strain ◽  
Space Model ◽  
Highly Nonlinear ◽  
Stress Changes

Abstract. The elastic response of many rocks to quasistatic stress changes is highly nonlinear and hysteretic, displaying discrete memory. Rocks also display unusual nonlinear response to dynamic stress changes. A model to describe the elastic behavior of rocks and other consolidated materials is called the Preisach-Mayergoyz (PM) space model. In contrast to the traditional analytic approach to stress-strain, the PM space picture establishes a relationship between the quasistatic data and a number density of hysteretic mesoscopic elastic elements in the rock. The number density allows us to make quantitative predictions of dynamic elastic properties. Using the PM space model, we analyze a complex suite of quasistatic stress-strain data taken on Berea sandstone. We predict a dynamic bulk modulus and a dynamic shear modulus surface as a function of mean stress and shear stress. Our predictions for the dynamic moduli compare favorably to moduli derived from time of flight measurements. We derive a set of nonlinear elastic constants and a set of constants that describe the hysteretic behavior of the sandstone.

scholarly journals Analysis of damage-plasticity model of concrete under uniaxial compression loading

2021 ◽  
Vol 10 (1) ◽  
pp. 29
Author(s):  
Mohammad Rafiqul Islam ◽  
Abbas Ali ◽  
Md. Jahir Bin Alam ◽  
Tanvir Ahmad ◽  
Salman Sakib
Keyword(s):  
Analytical Data ◽  
Strain Curve ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Compression Loading ◽  
Model Code ◽  
Concrete Damage ◽  
Two Phases

Concrete is a quasi-brittle material and shows different behavior in compression and tension. It shows elastic behavior at initial stage and damage-plasticity behavior beyond elastic limit. Therefore, development of material behavior model of concrete is a complex phenomenon. In this study, concrete damage plasticity theory has been described under experiment on concrete cylinder considering uni-axial compression loading and interpreted with analytical data calculated using CEB-FIP model code equation. The code has divided the stress-strain curve for concrete compression into three sections according to concrete’s elastic and non-elastic behaviors. Those three sections have been considered to calculate analytical data. In experiment, concrete behavior has been observed in two phases. The damage value for different stresses at the various points on the stress strain curve has been calculated. According to analytical data, the concrete shows elastic behavior up to 8.3MPa stress point and no damage occur in the concrete within the limit. However, in experimental data, concrete shows elastic behavior up to only 2.28MPa and damage occurred beyond the stress. Finally, the percentage of damage of concrete due to compression obtained from analysis and experiment has been assessed and compared. Above 32 percent of concrete damage is found for 22.5 MPa in both cases.  

Elastic response of Carbon Black reinforced polyester based composites using micromechanical models: Role of interphase

2022 ◽  
pp. 239779142110701
Author(s):  
Mehdi Karevan
Keyword(s):  
Carbon Black ◽  
Thermal Studies ◽  
Elastic Response ◽  
Elastic Behavior ◽  
Analytical Prediction ◽  
Morphological Studies ◽  
Micromechanical Models ◽  
The Impact ◽  
Carbon Based

Carbon-based reinforcements have been widely reported in improving mechanical properties of polymers. However, still few studies exist on the incorporation of the interphase as a result of the interfacial interactions into analytical prediction tools. To better understand the effect of interfacial interphase, this study compares and correlates the experimental mechanical response of polyester based composites filled with carbon black (CB) with the elastic behavior obtained from the micromechanical models. Mold cast composites of polyester reinforced with 0 wt%–10 wt% of CB were fabricated. To determine the length of cooperative rearranging region (CRR) as a measure of the interphase, thermal studies focusing on the variations in the specific heat capacity or the relaxation strength of the composites around the glass transition temperature ( Tg) range were performed using a thermodynamical model. Micromechanical models such as the Halpin-Tsai and Tandon-Weng were used to determine the Young’s modulus with respect to the CB wt% and diameter as well as the interphase thickness and modulus. The results exhibited the sensitivity of the models to the existence of the interphase as a secondary mechanism, which was correlated to the cross-link density and interfacial bonding. The impact results showed the decrease in the impact resistance upon the addition of higher filler loadings ascribed to the destroyed bonding at the interface and CBs agglomeration confirmed by morphological studies. The research results can be further utilized in the explanation of the changes in the elastic response of carbon-based reinforced thermosetting composites emphasizing the key role of interphase.

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