Flexural Model for Strain-Softening and Strain-Hardening Composites

2011 ◽  
pp. 265-300
Keyword(s):  
Strain Hardening ◽  
Strain Softening

Visco-Elastic-Plastic Constitutive Model for A7N01-T6 Alloy Welding and Analytical Solutions with Finite Element Codes

2013 ◽  
Vol 446-447 ◽  
pp. 284-287
Author(s):  
K.J. Song ◽  
Y.H. Wei ◽  
Z.B. Dong ◽  
K. Fang ◽  
W.J. Zheng ◽  
...  
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Strain Hardening ◽  
Strain Softening ◽  
Great Influence ◽  
Welding Process ◽  
Welding Residual Stress ◽  
Creep Equation ◽  
Maximum Deformation

This paper has established a viscoelasticplastic constitutive model for A7N01T6 alloy welding, which is temperature and deformation history dependent. The model uses elasticmixed hardening plastic and creep equation to describe the strain hardening at low temperatures and strain softening at high temperatures, respectively. Then it is applied for finite element numerical simulation of the welding process. By comparison with the conventional temperature dependent elasticperfectly plastic model, the overall longitudinal residual compressive plastic strain and the maximum deformation of welding sheet are larger. This is because that the plastic strain is mostly produced in high temperature range. Strain softening has great influence on the evolution of plastic strain. The compressive plastic strain during heating is larger than the tensile plastic strain during cooling. Strain hardening effect on welding residual strain and stress is almost negligible. Using the established constitutive model, welding residual stress and strain are in good agreement with the theoretical results.

An Associative and Non-Associative Anisotropic Bounding Surface Model for Clay

2012 ◽  
Vol 79 (3) ◽  
Author(s):  
Jianhong Jiang ◽  
Hoe I. Ling ◽  
Victor N. Kaliakin
Keyword(s):  
Mechanical Behavior ◽  
Strain Hardening ◽  
Strain Softening ◽  
Surface Model ◽  
Flow Rule ◽  
Reasonable Accuracy ◽  
Bounding Surface ◽  
Softening Behavior ◽  
Different Types ◽  
Undrained Behavior

An anisotropic elastoplastic bounding surface model with non-associative flow rule is developed for simulating the mechanical behavior of different types of clays. The non-associative flow rule allows for the simulation of not only strain-hardening but also strain-softening response. The theoretical framework of the model is given, followed by the verification of the model as applied to the experimental results of a strain-hardening Kaolin tested under different undrained stress paths. The undrained behavior of Boston Blue clay, which exhibits a strain-softening behavior, is also simulated. It is shown that the non-associative nature of the model gives more accurate results than those of the same model employing an associative flow rule, especially for normally consolidated Kaolin specimens. The results show that the model is also capable of simulating the strain-softening behavior of Boston blue clay with reasonable accuracy.

scholarly journals Study on Mechanical Properties of Gravelly Sand under Different Stress Paths

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Dongjie Zhang ◽  
Fei Luo ◽  
Zhanyuan Zhu ◽  
Jiaming Liu ◽  
Jing Li ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Stress Ratio ◽  
Void Ratio ◽  
Strain Softening ◽  
Triaxial Compression ◽  
Stress Path ◽  
Tibet Plateau ◽  
Shear Tests ◽  
Characteristic Angle ◽  
The Relationship

To investigate the strength and deformation characteristics of gravelly sand on the Qinghai-Tibet Plateau under different stress paths, a series of triaxial shear tests was conducted under confining pressures of 50–400 kPa in four types of stress path conditions of conventional triaxial compression (CTC) (drained and undrained), triaxial compression (TC), and reduced triaxial compression (RTC). We can see from the test results that gravelly sand samples show strain hardening and shear contraction under the CTC (drained), TC, and RTC during the shearing process but exhibit strain softening under the CTC (undrained). To explore the microscopic deformation mechanism of gravelly sand, a characteristic angle θ was defined to reflect the relative movement of soil particles. The relationship between principal stress ratio σ1/σ3 and characteristic angle θ and that between void ratio e and characteristic angle θ were derived. Subsequently, the relationship expression of stress ratio η (q/p) and void ratio e was established, and the trend of void ratio e with the stress path was studied. To describe the strain hardening and strain softening characteristics of gravelly sand in different stress paths, a new dilatancy equation was obtained by introducing the characteristic state stress ratio Mc into the dilatancy equation of the modified Cam-Clay model based on the state-dependent dilatancy theory. Finally, an elastoplastic constitutive model of gravelly sand was established by applying a nonassociate flow rule. All model parameters can be determined by triaxial shear tests under different stress paths, and the comparison results show that the proposed model can well reflect the mechanical behaviors of gravelly sand under different stress paths.

Dynamics of strain-hardening and strain-softening capsules in strong planar extensional flows via an interfacial spectral boundary element algorithm for elastic membranes

2009 ◽  
Vol 641 ◽  
pp. 263-296 ◽  
Author(s):  
W. R. DODSON ◽  
P. DIMITRAKOPOULOS
Keyword(s):  
Steady State ◽  
Strain Hardening ◽  
Boundary Element ◽  
Flow Rate ◽  
Strain Softening ◽  
Three Dimensional ◽  
Elastic Membranes ◽  
Extensional Flows ◽  
Element Algorithm ◽  
Fast Increase

In the present study we investigate the dynamics of initially spherical capsules (made from elastic membranes obeying the strain-hardening Skalak or the strain-softening neo-Hookean law) in strong planar extensional flows via numerical computations. To achieve this, we develop a three-dimensional spectral boundary element algorithm for membranes with shearing and area-dilatation tensions in Stokes flow. The main attraction of this approach is that it exploits all the benefits of the spectral methods (i.e. high accuracy and numerical stability) but without creating denser systems. To achieve continuity of the interfacial geometry and its derivatives at the edges of the spectral elements during the interfacial deformation, a membrane-based interfacial smoothing is developed, via a Hermitian-like interpolation, for both the interfacial shape and the membrane elastic forces. Our numerical results show that no critical flow rate exists for both Skalak and neo-Hookean capsules in the moderate and strong planar extension flows considered in the present study. As the flow rate increases, both capsules reach elongated ellipsoidal steady-state configurations; the cross-section of the Skalak capsule preserves its elliptical shape, while the neo-Hookean capsule becomes more and more lamellar. The curvature at the pointed edges of these elongated steady-state shapes shows a very fast increase with the flow rate. The large interfacial deformations are accompanied with the development of strong membrane tensions especially for the strain-hardening Skalak capsule; the computed increase of the membrane tensions with the flow rate or the shape extension can be used to predict rupture of a specific membrane (with known lytic tension) due to excessive tensions. The type of the experiment imposed on the capsule as well as the applied flow rate affect dramatically the time evolution of the capsule edges owing to the interaction of the hydrodynamic forces with the membrane tensions; when a spherical Skalak capsule is let to deform in a strong flow, very large edge curvatures (with respect to the steady-state value) are developed during the transient evolution.

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