A new damage model based on non-local displacements

In this work, a new damage model for concrete is proposed with an extension of the stress decomposition (limited to biaxial cases), to capture shear damage due to the opposite signed principal stresses. To extract the pure shear stress, the assumption is made that one component of the shear stress is a minimum absolute of the two principal stresses. The opposite signed principal stresses are decomposed into shear stress and uniaxial tensile/compressive stress. A local model is implemented in Abaqus UMAT and it is further extended to a non-local model by utilization of the gradient theory. The concept of three length scales (tension, compression, and shear) is kept the same as the recently proposed nonlocal damage model by the authors. The nonlocal model is implemented in the Abaqus UEL-UMAT subroutine with an eight-node quadrilateral user-defined element, having five degrees of freedom at corner nodes (displacement in X/Y direction and tensile/compressive and shear nonlocal equivalent strain) and two degrees of freedom at internal nodes. Some examples of a local model including uniaxial and biaxial loading are addressed. Also, five examples of mixed crack mode and mode-I cracking are presented to comprehensively show the performance of this model.

Download Full-text

Prediction of delamination crack growth in carbon/fiber epoxy composite laminates using non-local interface damage model

Mechanics & Industry ◽

10.1051/meca/2014030 ◽

2014 ◽

Vol 15 (4) ◽

pp. 293-300 ◽

Cited By ~ 4

Author(s):

Hassan Ijaz ◽

Muhammad Asad ◽

Laurent Gornet ◽

Syed Yasir Alam

Keyword(s):

Carbon Fiber ◽

Crack Growth ◽

Composite Laminates ◽

Epoxy Composite ◽

Damage Model ◽

Delamination Crack ◽

Interface Damage ◽

Non Local ◽

Carbon Fiber Epoxy

Download Full-text

Parameter Study of Concrete Impact Damage Model Based on DOE Analysis

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.502.451 ◽

2012 ◽

Vol 502 ◽

pp. 451-457

Author(s):

Jiang Bo Wang ◽

Qing Ming Zhang ◽

Cheng Liang Feng ◽

Wei Bing Li ◽

Heng Wang

Keyword(s):

Impact Velocity ◽

Impact Damage ◽

Damage Model ◽

Considerable Effect ◽

Model Material ◽

Parameter Study ◽

Material Parameters ◽

Model Based ◽

Two Parameters ◽

The Impact

By building up a debugging method about material parameters of concrete impact damage model based on DOE (Design of Experiments) analysis, this paper studies the influence of material parameters of concrete targets on the results of numerical simulation based on quantitative analysis, when the impact velocity is 300m/s and 850m/s respectively. It concludes that when the impact velocity of 300m/s, 5 parameters have considerable effect on the residual velocity of warhead, they are ，，， and . Of all 5 parameters, , and can be obtained by calculation therefore it only needs to debug two parameters and according to experiments. Finally, when the impact velocity is 300m/s or so, debug combining the experiments to get a set of concrete impact damage model material parameters to make the results of simulation and experiment anastomosis well.

Download Full-text