Study On Interphase-domain Macro-micro Progressive Damage Analytic Model For Composites

The stiffness, strength and macroscopic mechanical response of compositematerials are determined by the microscopic components and structures of them. It isnecessary to analyze the macroscopic mechanical response based on the microscopiccomponents and structures of composite materials in order to take full advantage ofthe designability for composte materials. The macro-micro multiscale model isbecoming a hot spot of research interest under this demand. These micromechanicalmethods are developed with high speed with in-depth understandings of mesoscopicstructures and performances of the composite materials. The Generalized Method ofCells (GMC) is a representative homogenized method and the Finite Volume DirectAveraging Miromechanics (FVDAM) is an emerging and promising micromechanicsmethod which is currently under-way to be developed. It is very easy to develop amacro/micro multiscale modle coubled with Finite Element Methods (FEM) due toboth of them are semi-analytical micromechanics methods.The general macro-micro progressive damage analytic models based on GMCand FVDAM are developed according to different structure levels in this paper. Themodels, in which more details such as structure, defects and damage can beconsidered, broke through the bottleneck of efficiency in traditional macro-micromodel. The material constants of unidirectional laminate, behavior of unidirectionallaminate under tensile/compressive loading, failure envelopes of composite laminatesand bearing strength of bolted laminates are studied by the analytic model presentedin this paper. The influence of micro-mechanical properties and structure ofcomponents such as fiber, matrix and interphase on the macro-mechanical propertiesare revealed. The main body of this paper is as follows,1. Four types of Representative Volume Element, including fiber, matrix andinterface, are constructed according to different fiber arrays, these models are used topredict the effective elastic properties of unidirectional composite laminate, then theeffects of micro-structure and properties of interface on the effective elasticproperties pridition of unidirectional composite laminate are studied. The accuracy ofthese models is anylized and verified by comparing the simulative value withexperimental data. Furthermore, the tensile/compressive failure behaviors arepredicted, and the predictive strengths with different RVEs are compared. Thedamage mechanism and failure modes are illustrated from micro-component levelsuch as stress of matrix and interface. Finally, the advantage and disadvantage inGMC model and FVDAM model are evaluated. 2. Macro/micro multi-scale analysis models based on the GMC and FVDAMseparately coupled with classical lamination theory were conducted to predict biaxialfailure envelopes of composite laminates, applying failure criteria such as Max-strain,Max-stress, Tsai-Hill and Tsai-Wu failure criteria at the constituent level. And thenthese multi-scale models were used to analyze the all of the examples in the WorldWide Failure Exercise (WWFE), including foure material systems, five layups andthe stress-strain curves under applied loadings. It is focused to compare the accuracyand applicability of GMC and FVDAM model separately and finally thehigh-performaces of these models are indicated.3. A specimen-level multiscale methodology based on GMC which isimplemented in ABAQUS through the user subroutine USDFLD has been developedto predict the progressive damage of composite bolted joint laminates. The three maintypes of failure modes (net-tension, shear-out and bearing failure) are simulated, andthe accuracy was verified through comparing the simulative results with experimentalfailure modes. Finally, the effect of geometry of specimen on the limit strength ofcomposite bolted joint laminates was studied, and the accuracy was demonstrated bybeing compared with experimental data.