Publications

@article{Chen2019b,
title = {Improved prediction of residual stress induced warpage in thermoset composites using a multiscale thermo-viscoelastic processing model},
author = {W Chen and D Zhang},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072086100&doi=10.1016%2fj.compositesa.2019.105575&partnerID=40&md5=72cd17914c7f1724398836121b04c01a},
doi = {10.1016/j.compositesa.2019.105575},
year = {2019},
date = {2019-01-01},
journal = {Composites Part A: Applied Science and Manufacturing},
volume = {126},
abstract = {A multiscale thermo-viscoelastic processing model is developed to predict the residual stress development in a thermoset composite due to curing. In the proposed modeling framework, a composite laminate is modeled as discrete layers of homogeneous laminae at the macroscale, while at each integration point of the homogeneous model, the constitutive relations of the lamina are determined through micromechanics using an Extended Concentric Cylinder Assemblage (ECCA) model in conjunction with the correspondence principle of viscoelasticity. Since analytical formulations are employed at the microscale, the proposed multiscale approach can efficiently predict the composite time-, temperature-, and cure-dependent responses during processing. The proposed model is employed to predict the warpage shape of an anti-symmetric laminate due to curing-induced residual stresses. Compared with other elastic processing models, the proposed processing model achieves an improved prediction of the warpage shape due to its capability to consider both curing history and stress relaxation during composite processing. © 2019},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Li2019953,
title = {A textile architecture-based hyperelastic model for rubbers reinforced by knitted fabrics},
author = {R Li and D Zhang},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058648459&doi=10.1007%2fs00707-018-2276-2&partnerID=40&md5=3471331dcbca3d2953d9b25089323441},
doi = {10.1007/s00707-018-2276-2},
year = {2019},
date = {2019-01-01},
journal = {Acta Mechanica},
volume = {230},
number = {3},
pages = {953-964},
abstract = {A new anisotropic hyperelastic model has been developed to model the deformation response of a knitted-fabric-reinforced rubber composite. The composite has a sandwich structure with a fiber net layer embedded in two rubber layers. Due to the architecture of the knitted fabric, the composite demonstrates an anisotropic hyperelastic response, which is modeled through a strain energy density function that incorporates the effects of deformed rubbers and stretched fibers. The rubber is considered as a neo-Hookean material, while the knitted fabrics are modeled as cords with negligible stiffness in bending. The effect of reinforcement comes from the conservation of the total length of the fiber cords. In addition, a slack variable is proposed to account for the effect of processing-induced fabric pre-stretch or fabric slack on the resulting composite response. This novel approach enables the determination of the constitutive behavior of the composite in closed form based on the constituent rubber and fiber properties and fabric architectures. The proposed analytical model is validated through a full 3D finite element (FE) model, in which the rubber and fiber reinforcement are modeled explicitly. Since the proposed model captures the key parameters that dictate the deformation response of knitted-fabric-reinforced composites, it can be employed as an efficient modeling tool to guide the design of rubbers and fabric architectures with targeted composite performance. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Pham2019,
title = {A three-dimensional progressive damage model for drop-weight impact and compression after impact},
author = {D C Pham and J Lua and H Sun and D Zhang},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068361496&doi=10.1177%2f0021998319859050&partnerID=40&md5=b2b6ea78739bbe20817f88ea7c82a4d1},
doi = {10.1177/0021998319859050},
year = {2019},
date = {2019-01-01},
journal = {Journal of Composite Materials},
abstract = {In this paper, an enhanced three-dimensional continuum damage mechanics model is applied to predict the drop-weight impact response and compression after impact failure of a fiber-reinforced polymer composite specimen. The three-dimensional progressive damage model incorporates a three-dimensional maximum stress criterion to predict the intra-ply damage initiation, followed by a fracture-energy-based smeared crack model to capture the post-peak softening behavior. Driven by the dominant through-the-thickness failure under impact loading, a three-dimensional continuum damage model is implemented for the three-dimensional solid element via its explicit material model for Abaqus (VUMAT) to capture the effect of three-dimensional stress state and the interaction of matrix cracking and delamination. Abaqus’ restart analysis capability is used to activate the compression after impact analysis using the final damage state from the dynamic impact analysis. Both the dynamic failure and the compression after impact are demonstrated via a suite of verification examples followed by the sensitivity analysis using distinct impact configurations. The predictive capability of the proposed three-dimensional damage model is first verified using a static open-hole tension test. Applications of the damage model are then demonstrated for simulations of the dynamic drop-weight tests and compression after impact tests. A comparative study on the developed method is performed using the results predicted from the open-source CompDam. A sensitivity study is also performed to demonstrate the impact energy-dependent failure mode. The proposed model has shown its advantages in performing a quick assessment of impact damage and its effects on the residual compressive strength. © The Author(s) 2019.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Chen2018153,
title = {A micromechanics-based processing model for predicting residual stress in fiber-reinforced polymer matrix composites},
author = {W Chen and D Zhang},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050624281&doi=10.1016%2fj.compstruct.2018.07.016&partnerID=40&md5=1fc3c8a541a15af29a3673007341f8ba},
doi = {10.1016/j.compstruct.2018.07.016},
year = {2018},
date = {2018-01-01},
journal = {Composite Structures},
volume = {204},
pages = {153-166},
abstract = {An experimentally validated, multi-physics and multi-scale processing model was developed to predict the residual stress buildup in a polymer matrix composite during manufacturing. At the macroscale, the composite was modeled as discrete layers of homogeneous, transversely isotropic laminae, while micromechanics was implemented at the subscale to compute the effective lamina responses based on the fiber and matrix properties through an Extended Concentric Cylinder Assemblage (ECCA) model. The composite temperature and Degree of Cure (DOC) distributions were solved by incorporating resin cure kinetics into heat transfer analysis, which were used in the subsequent stress analysis to determine the cure-dependent composite responses, including cure-dependent modulus, thermal strain, and chemical shrinkage. This integrated processing model was applied to predict the cure-induced warpage of a non-symmetric laminate. The proposed model, which incorporates resin cure kinetics, cure-dependent constitutive law, and tool-part interaction, demonstrates good agreement with the experiment on the prediction of the warpage curvatures. © 2018 Elsevier Ltd},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Heimbach20181,
title = {High performance resorbable composites for load-bearing bone fixation devices},
author = {B Heimbach and B Tonyali and D Zhang and M Wei},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042225085&doi=10.1016%2fj.jmbbm.2018.01.031&partnerID=40&md5=131a091248294549a10c11f4fb212cc7},
doi = {10.1016/j.jmbbm.2018.01.031},
year = {2018},
date = {2018-01-01},
journal = {Journal of the Mechanical Behavior of Biomedical Materials},
volume = {81},
pages = {1-9},
abstract = {Bone fractures are some of the most common injuries annually, and many require a fixation device to help properly heal. The present study focuses on developing a bioresorbable composite that has high strength and stiffness for bone fixation applications. To achieve this, a design of experiments was performed, testing the effect of long fiber reinforcement type, matrix type, matrix amount, and particle reinforcement amount on the flexural properties of the composite. Based on these results, the ideal resorbable long fiber reinforcement, particle reinforcement, and matrix material are degummed silk fibroin, hydroxyapatite, and polylactic acid, respectively. Through further optimizations of the particle reinforcement phase a flexural modulus and strength of 13.7 GPa and 437 MPa, respectively, was achieved. Both values are among the highest found in literature, with the strength far exceeding the requirement for a fixation device and the highest for such a bioresorbable composite material, showing great promise for use as a bioresorbable fixation device. © 2018},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zeng2017,
title = {Moisture-Responsive Wrinkling Surfaces with Tunable Dynamics},
author = {S Zeng and R Li and S G Freire and V M M Garbellotto and E Y Huang and A T Smith and C Hu and W R T Tait and Z Bian and G Zheng and D Zhang and L Sun},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018604698&doi=10.1002%2fadma.201700828&partnerID=40&md5=d6a8cf5ef182186a23fcb7f403ab1a23},
doi = {10.1002/adma.201700828},
year = {2017},
date = {2017-01-01},
journal = {Advanced Materials},
volume = {29},
number = {24},
abstract = {The wrinkle dynamics (such as reversibility and stability) of human skin are affected by the external stimuli, as well as the skin's structure and mechanical properties. Inspired by these tunable responses, three types of moisture-responsive wrinkle dynamics are achieved, for the first time, through a single film–substrate system. These dynamics include: (1) completely reversible wrinkles formation; (2) irreversible wrinkles formation I: the initially formed wrinkles can be permanently erased and never reappear; and (3) irreversible wrinkles formation II: once the wrinkles form, they can no longer be erased. The key to success is to control the stiffness and thickness ratios of the film and the substrate, and tailor the crosslink degree/gradient of the film to allow for moisture-dependent changes of modulus and swelling degree. These unique responsive dynamics motivate the invention of a series of optical devices triggered by moisture, including anticounterfeit tabs, encryption devices, water indicators, light diffusors, and antiglare films. This study also paves the road for further understanding of the skin wrinkling dynamics and manipulation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhang2017264,
title = {An experimentally validated computational model for progressive damage analysis of notched oxide/oxide woven ceramic matrix composites},
author = {D Zhang and P Meyer and A M Waas},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85000879104&doi=10.1016%2fj.compstruct.2016.11.001&partnerID=40&md5=12dce26910992624bb4619626831f8a5},
doi = {10.1016/j.compstruct.2016.11.001},
year = {2017},
date = {2017-01-01},
journal = {Composite Structures},
volume = {161},
pages = {264-274},
abstract = {The focus of this paper is to examine the effect of a notch on the failure response of an oxide/oxide ceramic matrix composite (CMC) subjected to room-temperature tensile loading. The CMC is made of aluminosilicate matrix reinforced by 3M Nextel™ 610 alumina fibers (AS/N610) that are woven into an eight-harness satin weave (8HSW) preform. Uniaxial tensile tests were carried out on both un-notched and single-edge-notched tensile (SENT) specimens of two different lay-ups, (0/90)S and (45/0/-45/0)S, using a hydraulically activated load frame. The digital image correlation (DIC) technique was utilized to map the deformation histories and identify the locations of strain concentration for both un-notched and SENT specimens. The experimental results were subsequently used to develop a lamina-level constitutive model for a single 8HSW ply that incorporates damage and fracture mechanics implemented through a finite element (FE) framework. A secant-modulus approach was employed to model the pre-peak nonlinear damage evolution, while the post-peak softening was modeled using the smeared crack approach (SCA). Utilizing the ply properties measured from the un-notched (0/90)S and (45/0/-45/0)S tension tests, the proposed computational model is able to predict the failure strength and strain localization in the SENT specimens. Such a predictive model can aid in the design of CMC structures and accelerate the development of CMCs for engineering applications. © 2016 Elsevier Ltd},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zeng2016,
title = {Bio-inspired sensitive and reversible mechanochromisms via strain-dependent cracks and folds},
author = {S Zeng and D Zhang and W Huang and Z Wang and S G Freire and X Yu and A T Smith and E Y Huang and H Nguon and L Sun},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978062249&doi=10.1038%2fncomms11802&partnerID=40&md5=74663552821d24b92043e84110ee8310},
doi = {10.1038/ncomms11802},
year = {2016},
date = {2016-01-01},
journal = {Nature Communications},
volume = {7},
abstract = {A number of marine organisms use muscle-controlled surface structures to achieve rapid changes in colour and transparency with outstanding reversibility. Inspired by these display tactics, we develop analogous deformation-controlled surface-engineering approaches via strain-dependent cracks and folds to realize the following four mechanochromic devices: (1) transparency change mechanochromism (TCM), (2) luminescent mechanochromism (LM), (3) colour alteration mechanochromism (CAM) and (4) encryption mechanochromism (EM). These devices are based on a simple bilayer system that exhibits a broad range of mechanochromic behaviours with high sensitivity and reversibility. The TCM device can reversibly switch between transparent and opaque states. The LM can emit intensive fluorescence as stretched with very high strain sensitivity. The CAM can turn fluorescence from green to yellow to orange as stretched within 20% strain. The EM device can reversibly reveal and conceal any desirable patterns.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhang2015321,
title = {Progressive damage and failure response of hybrid 3D textile composites subjected to flexural loading, part II: Mechanics based multiscale computational modeling of progressive damage and failure},
author = {D Zhang and A M Waas and C -F Yen},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943455979&doi=10.1016%2fj.ijsolstr.2015.06.033&partnerID=40&md5=12bc1c475468e9e405661b40ee8fe925},
doi = {10.1016/j.ijsolstr.2015.06.033},
year = {2015},
date = {2015-01-01},
journal = {International Journal of Solids and Structures},
volume = {75-76},
pages = {321-335},
abstract = {A mechanics based multiscale computational model is presented to predict the deformation, damage and failure response of hybrid 3D textile composites (H3DTCs) subjected to three-point bending. The geometry of the textile architecture was incorporated in a mesoscale finite element (FE) model, while the H3DTC was homogenized at the macroscale. The mesoscale model is a collection of repeat unit cells (RUCs) that are composed of different types of fiber tows embedded in a surrounding matrix. Matrix microdamage was modeled by a (pre-peak) nonlinear stress versus strain response, using a modified J2 deformation theory of plasticity incorporating a secant-modulus approach. Fiber tow pre-peak nonlinear response was computed using a novel, two-scale model, in which the subscale micromechanical analysis was carried out in closed-form based upon a unit cell of a fiber-matrix concentric cylinder. Consequently, the influence of matrix microdamage developing at the microscale manifests as the progressive degradation of fiber tow stiffness at the mesoscale. The smeared crack approach (SCA) was employed to model the post-peak softening of the constituents due to failure, including matrix macro-cracking, tow kinking, and tow breaking. This method offers a mesh objective result by relating the post-peak softening response to a traction-separation law that is associated with each failure mechanism through a characteristic length. Thus, the total energy release rate during failure in a continuum element is related to the fracture toughness of the material. The load-deflection responses, along with the progressive damage and failure events, including fiber tow kinking and rupture, are successfully predicted through the proposed computational model. In addition, the textile architecture-dependent effect, observed in the asymmetric H3DTCs, is also captured, demonstrating the predictive capability of the proposed modeling scheme. Since all the inputs are from the constituent level, the model is useful in understanding how the macroscopic response of H3DTCs is influenced by textile architecture and constituent properties. The experimental studies are presented in Part I of this two-part sequence (Zhang et al., 2015). © 2015 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhang2015309,
title = {Progressive damage and failure response of hybrid 3D textile composites subjected to flexural loading, part I: Experimental studies},
author = {D Zhang and A M Waas and C -F Yen},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943455361&doi=10.1016%2fj.ijsolstr.2015.06.034&partnerID=40&md5=464053575dcc7cf6f1b3a15060624073},
doi = {10.1016/j.ijsolstr.2015.06.034},
year = {2015},
date = {2015-01-01},
journal = {International Journal of Solids and Structures},
volume = {75-76},
pages = {309-320},
abstract = {This paper presents an experimental investigation of the deformation responses and failure mechanisms of hybrid 3D textile composites (H3DTCs) subjected to quasi-static three-point bending. The term "hybrid" refers to different constituent fiber tows, including carbon, glass, and Kevlar that are integrally woven into a single preform. Three different hybrid architectures, manufactured by varying the percentages and lay-ups of the constituent fiber tows, were examined to understand the effect of hybridization on the resulting performance enhancement, including the bending modulus, flexural yield stress, and strain to failure. All the architectures show a "plastic-like" nonlinear flexural response, indicating considerable damage tolerance and durability for this class of materials. It has been found that increasing the thickness of the specimens can increase the strain to failure in flexure. For an asymmetric H3DTC, which refers to an architecture that has carbon plies on one side and glass plies on the other (through-the-thickness), an increased flexural yield stress can be achieved by placing the glass on the side that experiences compressive straining in flexure, whereas the failure strain is reduced by placing the carbon on the side which experiences tension. Distributed matrix cracking was observed in regions of predominant tension through a digital image correlation (DIC) technique. Although the experimental results show architecture-dependent responses, fiber tow kinking, which develops on the compressive side of the specimen is determined to be a strength limiting mechanism for this class of materials subjected to flexural loading. The experimental results are subsequently used as a basis for developing a mechanics based multiscale computational model for H3DTC deformation, damage and failure response in flexure. Details of the modeling strategy and the development of damage and failure constitutive models are presented in Part II of this two-part sequence (Zhang et al., 2015). © 2015 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhang20141391,
title = {A micromechanics based multiscale model for nonlinear composites},
author = {D Zhang and A M Waas},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84898026268&doi=10.1007%2fs00707-013-1057-1&partnerID=40&md5=351ebbd0acba10dc02a082baee41e528},
doi = {10.1007/s00707-013-1057-1},
year = {2014},
date = {2014-01-01},
journal = {Acta Mechanica},
volume = {225},
number = {4-5},
pages = {1391-1417},
abstract = {A micromechanics model for fiber-reinforced composites that can be used at the subscale in a multiscale computational framework is established to predict the effective nonlinear composite response. Using a fiber-matrix concentric cylinder model as the basic repeat unit to represent the composite, micromechanics is used to relate the applied composite strains to the fiber and matrix strains by a six by six transformation matrix. The resolved spatial variations of the matrix fields are found to be in good agreement with corresponding finite element analysis results. The evolution of the composite nonlinear response is assumed to be governed by two scalar, strain-based variables that are related to the extreme value of an appropriately defined matrix equivalent strain, and the matrix secant moduli are used to compute the composite secant moduli for nonlinear analysis. The results from the micromechanics model are compared well with a full finite element analysis. The predictive capability of the proposed model is illustrated by two distinct fiber-reinforced material systems, carbon and glass, for the fiber volume fraction varying from 50 to 70 %. Since fully analytical solutions are utilized for the micromechanical analysis, the proposed method offers a distinct computational advantage in a multiscale analysis and is therefore suitable for large-scale progressive damage and failure analyses of composite material structures. © 2014 Springer-Verlag Wien.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhang201231009-1,
title = {Flexural behavior of a layer-to-layer orthogonal interlocked three-dimensional textile composite},
author = {D Zhang and A M Waas and M Pankow and C F Yen and S Ghiorse},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84894470451&doi=10.1115%2f1.4006501&partnerID=40&md5=77a4bfd484bfb0dfa1197e2357a14f2e},
doi = {10.1115/1.4006501},
year = {2012},
date = {2012-01-01},
journal = {Journal of Engineering Materials and Technology, Transactions of the ASME},
volume = {134},
number = {3},
pages = {31009-1-31009-8},
abstract = {The flexural response of a three-dimensional (3D) layer-to-layer orthogonal interlocked textile composite has been investigated under quasi-static three-point bending. Fiber tow kinking on the compressive side of the flexed specimens has been found to be a strength limiting mechanism for both warp and weft panels. The digital image correlation (DIC) technique has been utilized to map the deformation and identify the matrix microcracking on the tensile side prior to the peak load in the warp direction loaded panels. It has been shown that the geometrical characteristics of textile reinforcement play a key role in the mechanical response of this class of material. A 3D local-global finite element (FE) model that reflects the textile architectures has been proposed to successfully capture the surface strain localizations in the predamage region. To analyze the kink banding event, the fiber tow is modeled as an inelastic degrading homogenized orthotropic solid in a state of plane stress based on Schapery Theory (ST). The predicted peak stress is in agreement with the tow kinking stress obtained from the 3D FE model. © 2012 by ASME.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}