Crack Deflection at an Interface Between Two Orthotopic Media

1992 ◽  
Vol 59 (2S) ◽  
pp. S79-S87 ◽  
Author(s):  
V. Gupta ◽  
A. S. Argon ◽  
Z. Suo
Keyword(s):  
Material Constant ◽  
Crack Deflection ◽  
Material Parameters ◽  
Fiber Coating ◽  
Composite Systems ◽  
Interfacial Fracture Mechanics ◽  
Orthotropic Media ◽  
Stress And Deformation ◽  
Deflection Criteria ◽  
Brittle Composites

To achieve toughness in many brittle composites, crack deflection at interfaces is essential. For this, it is necessary to establish crack deflection criteria by employing the principles of interfacial fracture mechanics applicable to anisotropic pair of materials. Such an analysis, with two aligned orthotropic media, is considered here. The stress and deformation fields derived for such cases are shown to depend on material parameters λ and p for the two media and on the two so-called Dundur constants α and β. For β = 0, the dependence on λ and λ2 collapses to Λ = (λ1,/λ2)1/4. The delamination criterion is insensitive to λ, p, Λ, and β over practical ranges of these material parameters. Thus, generalized delamination charts become possible as a function of the bi-material constant a alone, which characterizes the elastic dissimilarity between the two media. Using these charts, it is possible to determine the desired level of the interface strength required in composite manufacturing in order to enhance the overall toughness of a composite. Furthermore, such charts can be used for the interfaces between fiber/coating, fiber /matrix, or matrix/coating, depending on which interface is of critical interest for the crack deflection. It is shown how these charts can be used to identify composite systems where it is possible to maximize both the transverse strength and the longitudinal toughness.

Research on Sliding Layer of Cross-Tensioned Prestressed Concrete Pavement

2014 ◽  
Vol 1004-1005 ◽  
pp. 1486-1491
Author(s):  
De Chen ◽  
Sen Han ◽  
Cheng Ling ◽  
Dong Sheng Zhang ◽  
Fu Yang Guan
Keyword(s):  
Coefficient Of Friction ◽  
Prestressed Concrete ◽  
Concrete Pavement ◽  
Plastic Film ◽  
Analysis Method ◽  
Material Parameters ◽  
Friction Tester ◽  
Optimum Material ◽  
Stress And Deformation ◽  
Testing Speed

A coefficient of friction tester (CFT) for the cross-tensioned prestressed concrete pavement (CTCP) sliding layer was designed and developed basing on the Amonton law. The CFT can obtain precise values of the CTCP sliding layer coefficient of friction. Meanwhile, the sand and polyethylene plastic film (SPPF) sliding layer which has already been used in CTCP experimental road was tested using the CFT. The best testing speed (1mm/min) for CFT was obtained with applying regression analysis method to the results. The optimum material parameters for the SPPF are the combination of 2.6 fineness modulus of sand, 10mm thickness of sliding layer, and 3 μm thickness of polyethylene plastic film (PPF). The optimum materials combination of the SPPF provides minimum coefficient of friction to the CTCP sliding layer which can reduce the stress and deformation of the CTCP slab.

Dependence of Thermal Stress Resistance on Material Parameters: Ceramic Composite Systems

1980 ◽  
pp. 397-411 ◽  
Author(s):  
P. F. Becher ◽  
D. Lewis ◽  
W. J. McDonough ◽  
R. W. Rice ◽  
G. E. Youngblood ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Stress Resistance ◽  
Ceramic Composite ◽  
Material Parameters ◽  
Composite Systems

A Parametric Investigation on the Neo-Hookean Material Constant

2014 ◽  
Vol 915-916 ◽  
pp. 853-857 ◽  
Author(s):  
Siti Hajar Mohd Yusop ◽  
Mohd Nor Azmi Ab Patar ◽  
Anwar P.P. Abdul Majeed ◽  
Jamaluddin Mahmud
Keyword(s):  
Constitutive Equation ◽  
Material Properties ◽  
Parametric Study ◽  
Strain Energy ◽  
Deformation Behaviour ◽  
Strain Energy Function ◽  
Material Constant ◽  
Hyperelastic Materials ◽  
Material Parameters ◽  
To Come

This paper assesses the Neo-Hookean material parameters pertaining to deformation behaviour of hyperelastic material by means of numerical analysis. A mathematical model relating stress and stretch is derived based on Neo-Hookeans strain energy function to evaluate the contribution of the material constant, C1, in the constitutive equation by varying its value. A systematic parametric study was constructed and for that purpose, a Matlab programme was developed for execution. The results show that the parameter (C1) is significant in describing material properties behaviour. The results and findings of the current study further enhances the understanding of Neo-Hookean model and hyperelastic materials behaviour. The ultimate future aim of this study is to come up with an alternative constitutive equation that may describe skin behaviour accurately. This study is novel as no similar parametric study on Neo-Hookean model has been reported before.

scholarly journals The influence of temperature on the small-strain viscous deformation mechanics of snow: a comparison with polycrystalline ice

2003 ◽  
Vol 37 ◽  
pp. 90-96 ◽  
Author(s):  
Carlo Scapozza ◽  
Perry A. Bartelt
Keyword(s):  
Power Law ◽  
Material Constant ◽  
Grain Boundary Sliding ◽  
Low Density ◽  
Compression Tests ◽  
Secondary Importance ◽  
Viscous Deformation ◽  
Material Parameters ◽  
Polycrystalline Ice ◽  
Deformation Mechanics

AbstractGlen’s law is commonly used to model the viscous deformation of polycrystalline ice. It is a power law that relates stress to viscous strain rate and contains three material parameters: n, a power-law exponent, Q, an activation energy, and A0, a material constant. Because polycrystalline ice is the constituent material of snow, it is to be expected that the viscous deformation mechanics of snow are related to the viscous behaviour of polycrystalline ice, especially under small strains and low strain rates when kinematic effects in the ice matrix like bond breakage, bond formation and grain sliding are of secondary importance. Based on 64 deformation-controlled compression tests on fine-grained snow in the density range 200–430kg m–3 and temperature range T = –20 to –2°C, we show that Glen’s law—with material parameters similar to those for polycrystalline ice—can be applied to model the viscous deformation of high-density snow However, the values of the ice material parameters are valid for densities above a relatively low density of 400 kg m–3; they are not valid for snow with densities below 360 kg m–3. We present the variation of n, Q and A for snow as a function of density and temperature. A possible explanation for this behaviour is that the ice grains in low-density snow are less constrained. Therefore, deformation mechanisms, such as grain-boundary sliding, increase in overall importance, leading to smaller n values and higher activation energies, Q. Although the material behaviour of low-density snow can be accurately modelled using a power law, the power-law parameters depart substantially from those of polycrystalline ice. The large variation of n and Q with temperature and density underscores the difficulty of predicting snow avalanches.

scholarly journals Increasing Necking Strain through Corrugation: Identifying Composite Systems That Can Benefit from Corrugated Geometry

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5175
Author(s):  
Mark Fraser ◽  
Hatem Zurob ◽  
Peidong Wu ◽  
Olivier Bouaziz
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Finite Element Modeling ◽  
Work Hardening ◽  
Strain Response ◽  
Reinforced Composites ◽  
Material Parameters ◽  
Composite Systems ◽  
Property Space ◽  
The Right

Under some circumstances, composites with a corrugated reinforcement geometry show larger necking strains compared to traditional straight reinforced composites. In this work, finite element modeling studies were performed for linearly hardening materials, examining the effect of material parameters on the stress–strain response of both corrugation and straight-reinforced composites. These studies showed that improvements in necking strain depend on the ability of the corrugation to unbend and to provide a boost in work hardening at the right time. It was found that there is a range of matrix yield strengths and hardening rates for which a corrugated geometry will improve the necking strain and also a lower threshold of reinforcement yield strength below which no improvement in necking strain is possible. In addition, benefit maps and surfaces were generated that show which regions of property space benefit through corrugation and the corresponding improvement in necking strain that can be achieved.

On interfacial waves in pre-stressed layered incompressible elastic solids

1995 ◽  
Vol 450 (1939) ◽  
pp. 319-341 ◽  
Keyword(s):  
Energy Function ◽  
High Frequency ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Bifurcation Equation ◽  
Interfacial Waves ◽  
Elastic Solids ◽  
Frequency Limit ◽  
Material Parameters ◽  
Stress And Deformation

Interfacial waves along the plane boundary between two pre-stressed incompressible elastic solids are considered. One of the solids is a half-space while the other has arbitrary uniform thickness. The principal axes of the underlying pure homogeneous deformation in the two solids are aligned, with one axis normal to the interface. For propagation along an in-plane principal axis, the dispersion equation is derived in respect of a general strain-energy function. Conditions on the pre-strain, pre-stress and material parameters that ensure the existence of a unique interfacial wavespeed at low frequencies are obtained, and it is shown that, in special circumstances, non-dispersive waves can exist at the low-frequency limit. Asymptotic results at the high-frequency limit are also obtained. For the case of equibiaxial pre-strain, more specific conditions are derived for the existence of interfacial waves at the low- and high-frequency asymptotes, and these provide information on the existence of waves for the whole frequency range. A particular feature of the structure considered is that it may act as a mechanical filter in different frequency regimes depending on the pre-strain, pre-stress and material parameters. When the wavespeed vanishes, the dispersion equation reduces to a bifurcation equation, solutions of which define states of stress and deformation which form boundaries of the region of stability of the underlying state of stress and deformation in the two materials for given material properties. The bifurcation equation is examined separately and an explicit bifurcation criterion is given for equibiaxial deformations. The results are illustrated graphically by considering several numerical examples based on a certain class of strain-energy functions, which includes the neo-Hookean strain-energy function. The results highlight low- and high-frequency features and demonstrate the influence of pre-stress and deformation on the multiplicity of propagating modes.

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