Yuvaraj P¹, A Ramachra Murthy², Nagesh R Iyer³, S.K. Sekar⁴, Pijush Samui⁵

CMC-Computers, Materials & Continua, Vol.41, No.3, pp. 193-214, 2014, DOI:10.3970/cmc.2014.041.193

Abstract This paper presents fracture mechanics based Artificial Neural Network (ANN) model to predict the fracture characteristics of high strength and ultra high strength concrete beams. Fracture characteristics include fracture energy (Gf), critical stress intensity factor (KIC) and critical crack tip opening displacement (CTODc). Failure load of the beam (Pmax) is also predicated by using ANN model. Characterization of mix and testing of beams of high strength and ultra strength concrete have been described. Methodologies for evaluation of fracture energy, critical stress intensity factor and critical crack tip opening displacement have been outlined. Back-propagation training technique has been employed for updating… More >

S. Liu¹, X. Liu^2,3, Y. Yuan², P. F. He¹, H. A. Mang^2,4

CMC-Computers, Materials & Continua, Vol.39, No.2, pp. 85-112, 2014, DOI:10.3970/cmc.2014.039.085

Abstract Autogenous shrinkage is defined as the bulk deformation of a closed, isothermal, cement-based material system, which is not subjected to external forces. It is associated with the hydration process of the cement paste. From the viewpoint of engineering practice, autogenous shrinkage deformations result in an increase of tensile stresses, which may lead to cracking of early-age concrete. Since concrete is a multi-phase composite with different material compositions and microscopic configurations at different scales, autogenous shrinkage does not only depend on the hydration of the cement paste, but also on the mechanical properties of the constituents and of their distribution. In… More >

P. Yuvaraj¹, A. Ramachandra Murthy², Nagesh R. Iyer³, Pijush Samui⁴, S.K. Sekar⁵

CMC-Computers, Materials & Continua, Vol.36, No.1, pp. 73-97, 2013, DOI:10.3970/cmc.2013.036.073

Abstract This paper presents Multivariate Adaptive Regression Splines (MARS) model to predict the fracture characteristics of high strength and ultra high strength concrete beams. Fracture characteristics include fracture energy (GF), critical stress intensity factor (KIC) and critical crack tip opening displacement (CTODc). This paper also presents the details of development of MARS model to predict failure load (Pmax) of high strength concrete (HSC) and ultra high strength concrete (UHSC) beam specimens. Characterization of mix and testing of beams of high strength and ultra strength concrete have been described. Methodologies for evaluation of fracture energy, critical stress intensity factor and critical crack… More >

Brett A. Bednarcyk¹, Phillip W. Yarrington², Steven M. Arnold³

CMC-Computers, Materials & Continua, Vol.35, No.3, pp. 229-254, 2013, DOI:10.3970/cmc.2013.035.229

Abstract Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer’s coupling with NASA’s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated.… More >

L. N. McCartney¹

CMC-Computers, Materials & Continua, Vol.35, No.3, pp. 183-227, 2013, DOI:10.3970/cmc.2013.035.183

Abstract Analytical stress transfer models are described that enable estimates to be made of the stress and displacement fields that are associated with fibre fractures or matrix cracks in unidirectional fibre reinforced composites. The models represent a clear improvement on popular shear-lag based methodologies. The model takes account of thermal residual stresses, and is based on simplifying assumptions that the axial stress in the fibre is independent of the radial coordinate, and similarly for the matrix. A representation for both the stress and displacement fields is derived that satisfies exactly the equilibrium equations, the required interface continuity equations for displacement and… More >

Jennifer D. Rhymer¹, Hyonny Kim¹

CMC-Computers, Materials & Continua, Vol.35, No.2, pp. 87-117, 2013, DOI:10.3970/cmc.2013.035.087

Abstract Polymer matrix composite structures are exposed to a variety of impact threats including hail ice. Internal delamination damage created by these impacts can exist in a form that is visually undetectable. This paper establishes an analysis methodology for predicting the onset of delamination damage in toughened carbon/epoxy composite laminates when impacted by high velocity ice spheres (hailstones). Experiments and analytical work focused on ice sphere impact onto composite panels have determined the failure threshold energy as a function of varying ice diameter and panel thickness, and have established the ability to predict the onset of delamination using cohesive elements in… More >

Chandra Veer Singh^1,*

CMC-Computers, Materials & Continua, Vol.34, No.3, pp. 227-249, 2013, DOI:10.3970/cmc.2013.034.227

Abstract A non-linear damage model is developed for the prediction of stiffness degradation in composite laminates due to transverse matrix cracking. The model follows the framework of a recently developed synergistic damage mechanics (SDM) approach which combines the strengths of micro-damage mechanics and continuum damage mechanics (CDM) through the so-called constraint parameters. A common limitation of the current CDM and SDM models has been the tendency to over-predict stiffness changes at high crack densities due to linearity inherent in their stiffness-damage relationships. The present paper extends this SDM approach by including higher order damage terms in the characterization of ply cracking… More >

A. Ataş¹, C. Soutis²

CMC-Computers, Materials & Continua, Vol.34, No.3, pp. 199-226, 2013, DOI:10.3970/cmc.2013.034.199

Abstract A strength prediction method is presented for double-lap single fastener bolted joints of cross-ply carbon fibre reinforced plastic (CFRP) composite laminates using cohesive zone elements (CZEs). Three-dimensional finite element models were developed and CZEs were inserted into subcritical damage planes identified from X-ray radiographs. The method makes a compromise between the experimental correlation factors (dependant on lay-up, stacking sequence and joint geometry) and three material properties (fracture energy, interlaminar strength and nonlinear shear stress-strain response). Strength of the joints was determined from the predicted load-displacement curves considering sub-laminate and plylevel scaling effects. The predictions are in a reasonable agreement with… More >

A Rama Chandra Murthy¹, Smitha Gopinath^1,2, Ashish Shrivastav¹, G. S. Palani¹, Nagesh R. Iyer¹

CMC-Computers, Materials & Continua, Vol.25, No.1, pp. 1-18, 2011, DOI:10.3970/cmc.2011.025.001

Abstract This paper presents methodologies for crack growth study and fatigue remaining life prediction of reinforced concrete structural components accounting for the corrosion effects. Stress intensity factor (SIF) has been computed by using the principle of superposition. At each incremental crack length, net SIF has been computed as the difference of SIF of plain concrete and reinforcement. The behaviour of reinforcement has been considered as elasto-plastic. Uniform corrosion rate has been assumed in the modeling. Corrosion effect has been accounted in the form of reduction in the diameter and modulus of elasticity of steel. Numerical studies have been carried out to… More >

Ke Jin¹, Yong Kou¹, Xiaojing Zheng^1,2

CMC-Computers, Materials & Continua, Vol.24, No.2, pp. 143-162, 2011, DOI:10.3970/cmc.2011.024.143

Abstract This paper is concerned with a 3-D general constitutive law of nonlinear magneto-thermo-elastic coupling for magnetostrictive materials. The model considered here is thermodynamically motivated and based on the Gibbs free energy function. A set of closed and analytical expressions of the constitutive relationships for the magnetostrictive materials are obtained, in which all parameters can be determined by those measurable experiments in mechanics and physics. Then the model can be simplified to two cases, i.e. magnetostrictive rods and films. It is found that the predictions from this model are in good accordance with the experimental data including both rods and films.… More >