Off-axis tensile strength and evaluation of the in-plane shear strength of paper

Holzforschung ◽  
2014 ◽  
Vol 68 (5) ◽  
pp. 583-590 ◽  
Author(s):  
Hiroshi Yoshihara ◽  
Masahiro Yoshinobu
Keyword(s):  
Tensile Strength ◽  
Shear Stress ◽  
Shear Strength ◽  
Stress Component ◽  
Shear Stress Component ◽  
Plane Shear ◽  
Dog Bone ◽  
Paper Filter ◽  
Failure Conditions ◽  
The Relationship

Abstract The off-axis tensile strength (OATS) of copy paper, filter paper, and sack paper was obtained from dog-bone specimens. The relationship between OATS and the off-axis angle (OAA) was predicted under several failure conditions. Additionally, the shear strengths (SS) of these papers were evaluated based on the results of OAT tests. The OATS could be accurately predicted under several Hill-type failure conditions. An equation for deriving the in-plane SS of these papers was proposed based on the tensile strength of the specimen with a 35° OAA, in which the contribution of the shear stress component was maximum.

Shear Strength of Fibrous Sheets: An Experimental Investigation

1997 ◽  
Vol 67 (8) ◽  
pp. 593-600 ◽  
Author(s):  
Ning Pan ◽  
Xiaoshan Zhang
Keyword(s):  
Experimental Investigation ◽  
Tensile Strength ◽  
Shear Strength ◽  
Anisotropic Materials ◽  
Strength Prediction ◽  
Plane Shear ◽  
Nonwoven Fabrics ◽  
Custom Made ◽  
Theoretical Predictions ◽  
The Relationship

This study of the shear strength of fibrous sheets first measures the in-plane shear strengths of various samples, including woven and nonwoven fabrics and paper, using a custom-made apparatus attached to an Instron tester. The structure of the apparatus and the measurement procedures are introduced in this article. The tested shear strength values are then compared with theoretical predictions from an earlier work. Discrepancies and possible causes are analyzed. Load-elongation curves for both tensile and shear are compared for individual fabrics and between fabrics. The relationship between the anisotropy of fabric tensile strength and the ratio of tested and predicted shear strength is explored. Also, the effect of fiber movement during textile deformation is examined. Finally, the original Tsai-Wu theory used for shear strength prediction of anisotropic materials is modified for application to the fibrous sheets, and the new predictions are provided for comparison.

scholarly journals An Experimental Study on Mechanical Behavior of Parallel Joint Specimens under Compression Shear

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Fei Wang ◽  
Ping Cao ◽  
Yu Chen ◽  
Qing-peng Gao ◽  
Zhu Wang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Failure Mode ◽  
Shear Failure ◽  
Strain Curve ◽  
Shear Loading ◽  
Plane Shear ◽  
Joint Spacing ◽  
Dip Angle ◽  
Joint Inclination

In order to investigate the influence of the joint on the failure mode, peak shear strength, and shear stress-strain curve of rock mass, the compression shear test loading on the parallel jointed specimens was carried out, and the acoustic emission system was used to monitor the loading process. The joint spacing and joint overlap were varied to alter the relative positions of parallel joints in geometry. Under compression-shear loading, the failure mode of the joint specimen can be classified into four types: coplanar shear failure, shear failure along the joint plane, shear failure along the shear stress plane, and similar integrity shear failure. The joint dip angle has a decisive effect on the failure mode of the specimen. The joint overlap affects the crack development of the specimen but does not change the failure mode of the specimen. The joint spacing can change the failure mode of the specimen. The shear strength of the specimen firstly increases and then decreases with the increase of the dip angle and reaches the maximum at 45°. The shear strength decreases with the increase of the joint overlap and increases with the increase of the joint spacing. The shear stress-displacement curves of different joint inclination samples have differences which mainly reflect in the postrupture stage. From monitoring results of the AE system, the variation regular of the AE count corresponds to the failure mode, and the peak value of the AE count decreases with the increase of joint overlap and increases with the increase of joint spacing.

Characterization of Thermally Induced Stress in IC Packages Using PiFETs Over a Temperature Range of −180°C to 80°C

2014 ◽  
Vol 2014 (1) ◽  
pp. 000500-000504 ◽  
Author(s):  
Francy J. Akkara ◽  
Uday S. Goteti ◽  
Richard C. Jaeger ◽  
Michael C. Hamilton ◽  
Michael J. Palmer ◽  
...  
Keyword(s):  
Shear Stress ◽  
Stress Component ◽  
Shear Stress Component ◽  
Thermally Induced ◽  
Temperature Changes ◽  
Temperature Range ◽  
Induced Stress ◽  
Highly Sensitive ◽  
Stress Components

In certain applications, IC packages may be exposed to extreme temperatures and knowledge of thermally induced stress aids the prediction of performance degradation or failure of the IC. In the devices that are used in extreme conditions, the stress is caused mainly by the mismatch in expansion of various materials triggered by the different coefficients of thermal expansion. This work performed in this study is conducted using NMOS current mirror circuits that are cycled through a wide temperature range of −180°C to 80°C. These circuits are highly sensitive to stress and provide well-localized measurements of shear stress. The sensors are fabricated in such a way that the effects of certain stress components are isolated. These sensors are also temperature compensated so that only the effect of mechanical stress components is observed and changes in device performance due to temperature changes are minimal. Current readings obtained from the sensors are used to extract the shear stress component. Finite element simulations, using expected materials performance parameter information were also performed for similar packages and these results are compared to the measured results.

scholarly journals Distribution Pattern of Anchorage Stress and Water Sensitivity Analysis of Red Clay

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lifeng Li ◽  
Weili Gong ◽  
Huilin Deng ◽  
Xiaohu Zhang ◽  
Gan Li
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Distribution Pattern ◽  
Water Content ◽  
Exponential Distribution ◽  
Red Clay ◽  
Anchor Cable ◽  
Water Sensitivity ◽  
The Relationship ◽  
Single Exponential

Red clay is a special soil layer with complex engineering properties distributed in tropical and subtropical regions. An anchor cable support is a common form of red clay slope support. The effectiveness of the anchor cable support is mainly determined by the anchoring force provided by the red clay stratum. Increase of the water content will lead to the rapid deterioration of the mechanical properties of red clay, which will lead to the reduction of the anchoring force of the slope anchor cable and lead to the failure of the support. Based on the classical Phillips and uniform anchorage shear stress distribution theory, this paper puts forward a uniform-exponential distribution pattern of anchorage shear stress according to the specific characteristics of red clay by using the characteristics of the peak shear strength and residual shear strength of the rock and soil mass. With increasing anchorage force, the dynamic evolution (single exponential distribution ⟶ double single exponential distribution ⟶ uniform index exponential complex distribution ⟶ uniform distribution) of the anchorage shear stress is analysed. Based on the peak and residual test of the cohesive force and internal friction angle, the relationship between the anchoring force and buried depth and water content is established by analysing the factors influencing the anchoring force. It can be found from the field test that, according to the relationship established, the limit anchorage force of the anchor cable in the red clay stratum can be calculated and the water sensitivity of the anchor cable’s limit anchorage force can be quantitatively analysed.

Response of Honeycombs Subjected to In-Plane Shear

2016 ◽  
Vol 83 (6) ◽  
Author(s):  
Youming Chen ◽  
Raj Das ◽  
Mark Battley
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Young’S Modulus ◽  
Cell Walls ◽  
Young's Modulus ◽  
Constitutive Relations ◽  
Length Ratio ◽  
Plane Shear ◽  
Base Materials ◽  
Vertical Cell

Study on the response of honeycombs subjected to in-plane shear helps establish the constitutive relations for honeycombs and shed light on the mechanics of cellular materials. The present study explores the nonlinear elastic response of honeycombs under in-plane shear by analyzing the large deflection of cell walls in a unit cell. Governing equations are established which relate the macroscopic response of honeycombs to the deflection of cell walls. Solving these equations, the behavior of regular honeycombs under in-plane shear along horizontal (X) and vertical (Y) directions was investigated. It is found that the response of regular honeycombs under in-plane shear depends on the nondimensional shear stress which is a parameter combining the thickness-to-length ratio of cell walls, the Young's modulus of base materials, and macroscopic shear stress. Lateral shrinking is a distinctive characteristic for honeycombs under in-plane shear, which should be taken into account when establishing constitutive relations and performing simple shear experiments. Expressions for predicting the shear strength of honeycombs are formulated in this paper. It is noted that the normalized shear strength of regular honeycombs depends on two ratios: the thickness-to-length ratio of cell walls and the ratio of Young's modulus to yield strength of base materials, and the former has a dominant effect. By comparing honeycombs with cell walls of uniform thickness against honeycombs with vertical cell walls of double thickness, it is found that doubling the thickness of vertical cell walls of honeycombs increases their shear strength along horizontal (X) direction nearly twice, but does not improve the shear strength that much along the vertical (Y) direction.

Fabrication and Mechanical Properties of Glass Fiber/Epoxy Nanocomposites

2006 ◽  
Vol 505-507 ◽  
pp. 37-42 ◽  
Author(s):  
Jia Lin Tsai ◽  
Jui Ching Kuo ◽  
Shin Ming Hsu
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Shear Strength ◽  
Glass Fiber ◽  
Shear Failure ◽  
Epoxy Nanocomposites ◽  
Plane Shear ◽  
Epoxy Nanocomposite ◽  
Transverse Normal Stress ◽  
Mechanical Mixer

This research is aimed to fabricate glass fiber/epoxy nanocomposites containing organoclay as well as to understand the organoclay effect on the in-plane shear strength of the nanocomposites. To demonstrate the organoclay effect, three different loadings of organoclay, were dispersed in the epoxy resin using mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were prepared by impregnating the organoclay epoxy mixture into the dry glass fiber through a vacuum hand lay-up process. Off-axis block glass/epoxy nanocomposites were tested in compression to produce in-plane shear failure. It is noted only the specimens showing in-plane shear failure mode were concerned in this study. Through coordinate transformation law, the uniaxial failure stresses were then converted to a plot of shear stress versus transverse normal stress from which the in-plane shear strength was obtained. Experimental results showed that the fiber/epoxy nanocomposite exhibit higher in-plane shear strength than the conventional composites. This increased property could be ascribed to the enhanced fiber/matrix adhesion promoted by the organoclay.

Study on the Relationship between Soil-Cement Parameters and Unconfined Compressive Strength

2011 ◽  
Vol 255-260 ◽  
pp. 4012-4016
Author(s):  
Jun Qing Ma ◽  
You Xi Wang
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Shear Strength ◽  
Unconfined Compressive Strength ◽  
Deformation Modulus ◽  
Soil Cement ◽  
Strength And Deformation ◽  
Cement Soil ◽  
Relationship Of ◽  
The Relationship

This paper studies relationship between soil-cement parameters and unconfined compressive strength. The research in tensile strength and deformation modulus of soil-cement is an important basis for soil-cement failure mechanism and intensity theory. They also impact cracks, deformation and durability of cement-soil structure. Shear strength and deformation of soil-cement is important to the destruction analysis and finite element calculations. Therefore it needs to study on tensile strength, shear strength and deformation modulus of soil-cement. Based on previous experiments, the relationship of tensile strength, shear strength, deformation modulus and unconfined compressive strength of soil-cement are quantitatively studied.

The Influence of Turbulence Memory on Idealized Tornado Simulations

2020 ◽  
Vol 148 (12) ◽  
pp. 4875-4892
Author(s):  
Aaron Wang ◽  
Ying Pan ◽  
Paul M. Markowski
Keyword(s):  
Boundary Condition ◽  
Shear Stress ◽  
Stress Component ◽  
Lower Boundary ◽  
Surface Friction ◽  
Surface Shear Stress ◽  
Normal Surface ◽  
Shear Stress Component ◽  
Surface Shear ◽  
Lower Boundary Condition

AbstractSurface friction contributes to tornado formation and maintenance by enhancing the convergence of angular momentum. The traditional lower boundary condition in atmospheric models typically assumes an instant equilibrium between the unresolved stress and the resolved shear. This assumption ignores the physics that turbulent motions are generated and dissipated at finite rates—in effect, turbulence has a memory through its lifetime. In this work, a modified lower boundary condition is proposed to account for the effect of turbulence memory. Specifically, when an air parcel moves along a curved trajectory, a normal surface-shear-stress component arises owing to turbulence memory. In the accompanying large-eddy simulation (LES) of idealized tornadoes, the normal surface-shear-stress component is a source of additional dynamic instability, which provides an extra pathway for the development of turbulent motions. The influence of turbulence memory on the intensity of quasi-steady-state tornadoes remains negligible as long as assumptions employed by the modified lower boundary condition hold over a relatively large fraction of the flow region of interest. However, tornadoes in a transient state may be especially sensitive to turbulence memory.Significance StatementFriction between the wind and the ground can influence atmospheric phenomena in important ways. For example, surface friction can be a significant source of rotation in some thunderstorms, and it can also help to intensify rotation when rotation is already present. Unfortunately, the representation of friction’s effects in atmospheric simulations is especially error-prone in phenomena characterized by rapid temporal evolution or strong spatial variations. Our work explores a new framework for representing friction to include the effect of the so-called turbulence memory. The approach is tested in idealized tornado simulations, but it may be applied to a wide range of atmospheric vortices.

Micromechanical analysis of longitudinal and shear strength of composite laminae

2020 ◽  
Vol 54 (30) ◽  
pp. 4853-4873 ◽  
Author(s):  
Lucas L Vignoli ◽  
Marcelo A Savi ◽  
Pedro MCL Pacheco ◽  
Alexander L Kalamkarov
Keyword(s):  
Experimental Data ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Shear Strength ◽  
The Other ◽  
Closed Form Expression ◽  
Plane Shear ◽  
Longitudinal Tensile Strength ◽  
Wide Range ◽  
Micromechanical Models

The analysis of several micromechanical models for estimating strength of composite laminae is presented. Longitudinal tensile, compressive and in-plane onset shear strengths are analytically estimated and compared with experimental data available in the literature. The tensile longitudinal load predominantly induces rupture of fibers. On the other hand, the compressive strength is highly influenced by fiber misalignment, inducing a wide range of failure mechanisms. The material response to in-plane shear presents a strong nonlinear response. The estimation of longitudinal tensile strength based on the rule of mixture approaches is compared with 27 experimental data. A novel improvement is proposed assuming that in situ strength of fiber is smaller than fiber strength measured individually due to manufacturing induced damage. For the in-plane shear, 6 models are compared with 10 experimental stress-strain curves, including a novel closed-form expression based on the concentric cylinders model. Finally, for the longitudinal compressive strength, 8 micromechanical models, including a novel model to estimate misalignment effect in fiber crushing, are compared with 61 experimental data are analyzed. Results indicate that the minimal average error for the longitudinal tensile strength is 12.4% while for the compressive strength it is 15%. For the shear strength, the closest prediction depends on the strength definition and the proposed damage onset strength presents the best predictions. In general, the newly proposed models present the best estimations compared with the other models.

scholarly journals Experimental study on granite acoustic emission and micro-fracture behavior with combined compression and shear loading: phenomenon and mechanism

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yue Cao ◽  
Jinhai Xu ◽  
Liang Chen ◽  
Peng Wu ◽  
Faiz Shaikh
Keyword(s):  
Shear Stress ◽  
Acoustic Emission ◽  
Fracture Mode ◽  
Inclination Angle ◽  
Fracture Behavior ◽  
Shear Failure ◽  
Stress Component ◽  
Shear Loading ◽  
Shear Stress Component ◽  
Microcrack Initiation

AbstractOne element that is essential to consider in underground mining engineering applications is the possibility of pillar failure, which can result in deadly geological disasters, including earthquakes and surface subsidence. Pillars are commonly present under an inclined state and are significantly dependent upon combined compression and shear loading. However, many scholars regard the pure uniaxial compression strength (UCS) of rock as the main evaluation index of pillar strength, which is inconsistent with the field practice. Hence, the present study developed a novel combined compression and shear test (C-CAST) system, which was applied in the investigative acoustic emission (AE) experiments to characterize the failure mechanism and micro-fracture behavior of granite specimens at different inclination angles. The experimental results presented the exponential decrease of UCS of inclined specimens with increase in the shear stress component. Changes in the inclination angle with a range of 0°–10° produced a splitting-shear failure fracture mode from the initial splitting failure. In comparison, an increase in the inclination angle from 10° to 20° produced a single shear failure fracture mode from the initial combined splitting-shear failure. The specimens exhibited nonlinearly reduced microcrack initiation (CI) and damage (CD) thresholds following an increase in the inclination angle, suggesting the dependence of the microcrack initiation and propagation on the shear stress component. The ratio of CI and CD thresholds to inclined UCS varies within a certain range, indicating that the ratio may be an inherent property of granite specimens and is not affected by external load conditions. Additionally, the rock fracture behavior was largely dependent upon the mechanism of shear stress component, as validated by the microcrack initiation and growth. Finally, a modified empirical formula for pillar strength is proposed to investigate the actual strength of inclined pillar. Results of a case study show that the modified formula can be better used to evaluate the stability of inclined pillars.

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