Guang Chen^1,*, Keqin Ding¹, Qibo Feng², Xinran Yin¹, Fangxiong Tang¹

Structural Durability & Health Monitoring, Vol.13, No.3, pp. 289-301, 2019, DOI:10.32604/sdhm.2019.05144

Abstract The grating ends bonding fiber Bragg grating (FBG) sensor has been widely used in sensor packages such as substrate type and clamp type for health monitoring of large structures. However, owing to the shear deformation of the adhesive layer of FBG, the strain measured by FBG is often different from the strain of actual matrix, which causes strain measurement errors. This investigation aims at improving the measurement accuracy of strain for the grating ends surface-bonded FBG. To fulfill this objective, a strain transfer equation of the grating ends bonding FBG is derived, and a theoretical model of the average strain… More >

Liu Yang¹, Jie Han, M. P. Anantram, Richard L. Jaffe

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.5, pp. 675-686, 2002, DOI:10.3970/cmes.2002.003.675

Abstract Bonding geometry and bandgap of carbon nantotubes under uniaxial and torsional deformation are studied computationally for nanotubes of various chiralities and diameters. Bonding geometries are obtained with Tersoff-Brenner potential from molecular mechanics simulations. Bandgaps as function of strain are calculated from the molecular mechanics structures using one (p) and four (2s and 2p_x, 2p_y, 2p_z) orbital tight-binding models. For small strains, the bandgap results are qualitatively consistent with those predicted by the one orbital analytical model. Response of the electronic properties of nanotubes to large strains is characterized by a change in sign of d(bandgap)/d(strain). These originate from either quantum… More >

Poonam Trivedi¹, Jens Schaller², Jan Gustafsson¹, Pedro Fardim^1,3*

Journal of Renewable Materials, Vol.5, No.5, pp. 400-409, 2017, DOI:10.7569/JRM.2017.634143

Abstract In the present study, we report the supramolecular design of cellulose-sulfonate hydrogel beads by blending water soluble sodium cellulose ethyl sulfonate (CES) with the pretreated cellulose in sodium hydroxide-ureawater solvent system at −6 °C followed by coagulation in the 2M sulfuric acid system. The increasing of CES amount from 10% to 90% had a substantial effect on the viscosity and storage (G′) and loss (G″) moduli of the blended solutions. The CES concentration up to 50% in blends led to the formation of physically stable hydrogels after coagulation in acidic medium at pH-1 and showed the retention of nearly the… More >

Gengmu Ruan¹, Haibei Xiong^1,*, Jiawei Chen¹

Structural Durability & Health Monitoring, Vol.13, No.2, pp. 227-246, 2019, DOI:10.32604/sdhm.2019.04743

Abstract In this paper, bending performance and rolling shear properties of cross-laminated timber (CLT) panels made from Canadian hemlock were investigated by varied approaches. Firstly, three groups of bending tests of three-layer CLT panels with different spans were carried out. Different failure modes were obtained: bending failure, rolling shear failure, bonding line failure, local failure of the outer layer and mixed failure mode. Deflection and strain measurements were employed to calculate the global and local modulus of elastic (MOE), compared with the theoretical value. In addition, a modified compression shear testing method was introduced to evaluate the rolling shear strength and… More >

B.R.Kim¹ and H.K.Lee^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.47, No.3, pp. 253-282, 2009, DOI:10.3970/cmes.2009.047.253

Abstract Damage characteristic of particulated ductile composites is a complex evolutionary phenomenon that includes particle debonding and void evolution with the accumulation of the plastic straining of the ductile matrix. In this paper, a micromechanical elastoplastic damage model for ductile matrix composites considering gradually incremental damage (particle debonding and void evolution) is proposed to predict the overall elastoplastic behavior and damage evolution in the composites. The constitutive damage model proposed in an earlier work by the authors [Kim and Lee (2009)] considering particle debonding is extended to accommodate the gradually incremental damage and elastoplastic behavior of the composites. On the basis… More >

E. H. Glaessgen¹, W.T. Riddell², I. S. Raju¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.1, pp. 103-116, 2002, DOI:10.3970/cmes.2002.003.103

Abstract The effects of several critical assumptions and parameters on the computation of strain energy release rates for delamination and debond configurations modeled with plate elements have been quantified. The method of calculation is based on the virtual crack closure technique (VCCT), and models of the upper and lower surface of the delamination or debond that use two-dimensional (2D) plate elements rather than three-dimensional (3D) solid elements. The major advantages of the plate element modeling technique are a smaller model size and simpler configurational modeling. Specific issues that are discussed include: constraint of translational degrees of freedom, rotational degrees of freedom… More >

R. Han¹, M.S. Ingber¹, H.L. Schreyer¹

CMC-Computers, Materials & Continua, Vol.4, No.3, pp. 163-176, 2006, DOI:10.3970/cmc.2006.004.163

Abstract Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interfaces in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones and the propagation of cracks… More >

Qiubao Ouyang¹, Di Zhang^1,2, Xinhai Zhu³, Zhidong Han³

CMC-Computers, Materials & Continua, Vol.41, No.1, pp. 37-54, 2014, DOI:10.3970/cmc.2014.041.037

Abstract The present work is to investigate the failure mechanisms in the deformation of silicon carbide (SiC) particle reinforced aluminum Metal Matrix Composites (MMCs). To better deal with crack growth, a new numerical approach: the MLPG-Eshelby Method is used. This approach is based on the meshless local weak-forms of the Noether/Eshelby Energy Conservation Laws and it achieves a faster convergent rate and is of good accuracy. In addition, it is much easier for this method to allow material to separate in the material fracture processes, comparing to the conventional popular FEM based method. Based on a statistical method and physical observations,… More >

Paria Naghipour¹, Evan J. Pineda², Steven M. Arnold²

CMC-Computers, Materials & Continua, Vol.35, No.1, pp. 17-33, 2013, DOI:10.3970/cmc.2013.035.017

Abstract The micromechanics theory, generalized method of cells (GMC), was employed to simulate the debonding of fiber/matrix interfaces, within a repeating unit cell subjected to global, cyclic loading, utilizing a cyclic crack growth law. Cycle dependent, interfacial debonding was implemented as a new module to the available GMC formulation. The degradation of interfacial stresses with applied load cycles was achieved via progressive evolution of the interfacial compliance A periodic repeating unit cell, representing the fiber/matrix architecture of a composite, was subjected to combined normal and shear loadings, and degradation of the global transverse stress in successive cycles was monitored. The obtained… More >