Computationally-efficient multiscale models for progressive failure and damage analysis of composites

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Elastoplastic and progressive failure analysis of fiber-reinforced composites via an efficient nonlinear microscale model

This paper presents numerical results concerning the nonlinear and failure analysis of fiber-reinforced composites. The micromechanical framework exploits a class of refined 1D models based on the Carrera Unified Formulation (CUF) having a variable kinematic description. The recently developed CUF micromechanics is a framework for the nonlinear modeling and exploits the ability of the CUF to predict accurate 3D stress fields with reduced computational overheads. The present formulation features the von Mises J2 theory for the pre-peak nonlinearity observed in matrix constituents, and the crack-band theory to capture the damage progression. Numerical examples and comparisons with results from literature assess the accuracy and efficiency of the proposed framework. The paper highlights the applicability of CUF models as an efficient micromechanical platform for nonlinear and progressive failure analysis for fiber-reinforced composites with potentially major advantages in the perspective of multiscale modeling

Numerical Simulation of Failure in Fiber Reinforced Composites

This paper presents numerical results concerning the failure analysis of fiber-reinforced composites. In particular, damage initiation and progressive failure are considered. The numerical framework is based on the CUF advanced structural models and the component-wise approach. Such models are employed at all scales. In other words, the same structural framework is employed for macro-, meso-, and microscales. Two approaches are assessed, including direct numerical simulations via micromechanical homogenization analysis and two-scale analysis. The results are compared with those from literature and attention is paid to the evaluation of the computational efficiency of the present numerical framework. In fact, 3D-like accuracy is sought with a reduced computational effort

Fast two-scale computational model for progressive damage analysis of fiber reinforced composites

A fast two-scale finite element framework based on refined finite beam models for progressive damage analysis (PDA) of fiber reinforced composite is presented. The framework consists of a macroscale model to define the structural-level components, interfaced with a second sub-scale model at the fiber-matrix level. Refined finite beam elements are based on Carrera Unified Formulation (CUF), a hierarchical formulation which offers a procedure to obtain refined structural theories that account for variable kinematic description. The representative volume element (RVE) at the subscale is modeled with real material, e.g., fiber and matrix with details about packing and heterogeneity. Component-Wise approach (CW), an extension of refined beam kinematics based on Lagrange-type polynomials is used to model the constituents in the subscale. Each constituent in the subscale is modeled by the same finite element in the framework of the CW. The energy based crack band theory (CBT) is implemented within the subscale constitutive laws to predict the damage propagation in individual constituents. The communication between the two scales is achieved through the exchange of strain, stress and stiffness tensor at every integration point in the macroscale model. The efficiency of the framework is derived from the ability of CUF models to provide accurate three-dimensional displacement and stress fields at a reduced computational cost (approximately one order of magnitude of degrees of freedom less as compared to standard 3D brick elements). Numerical predictions are validated against the experimental results

Computationally-efficient multiscale models for progressive failure and damage analysis of composites

A class of computationally-efficient tools to undertake progressive failure and damage analysis of composites across scales is presented. The framework is based on a class of refined one-dimensional (1D) theories referred to as the Carrera Unified Formulation (CUF), a generalized hierarchical formulation that generates a class of refined structural theories through variable kinematic description. 1D CUF models can provide accurate 3D-like stress fields at a reduced computational cost, e.g., approximately one to two orders of magnitude of degrees of freedom less as compared to standard 3D brick elements. The effectiveness of 1D CUF models to undertake physically nonlinear simulation is demonstrated through a class of problems with varying constitutive models. The virtual testing platform consists of a variety of computational tools such as failure index evaluations using component-wise modeling approaches (CUF-CW), CUF-CW micromechanics, concurrent multiscale framework, interface, and impact modeling. Failure index evaluation of a class of composite structures underlines the paramount importance of the accurate stress resolutions. Within the micromechanical framework, the Component-Wise approach (CW) is utilized to represent various components of the RVE. The crack band theory is implemented to capture the damage propagation within the constituents of composite materials and the pre-peak nonlinearity within the matrix constituents is modeled using the $J_2$ von-Mises theory. A novel concurrent multiscale framework is developed for nonlinear analysis of fiber-reinforced composites. The two-scale framework consists of a macro-scale model to describe the structural level components, e.g, open-hole specimens, coupons, using CUF-LW models and a sub-scale micro-structural model encompassed with a representative volume element (RVE). The two scales are interfaced through the exchange of strain, stress and stiffness tensors at every integration point in the macro-scale model. Explicit finite element computations at the lower scale are efficiently handled by the CUF-CW micromechanics tool. The macro tangent computation based on perturbation method which leads to meliorated performances. A novel numerical framework to simulate progressive delamination in laminated structures based on component-wise models is presented. A class of higher-order cohesive elements along with a mixed-mode cohesive constitutive law are integrated within the CUF-CW framework to simulate interfacial cohesive mechanics between various components of the structure. A global dissipation energy-based arc -length method to trace the complex equilibrium path exhibited by delamination problem. The capabilities of the framework are further extended through the introduction of contact kinematics to handle impact problems. A combination of the above tools is used to obtain an accurate material response of the structure in the non-linear regime, from the structural level i.e. macro-scale to the material constituent level i.e. the micro-scale, in a computationally efficient manner, providing a suitable virtual testing environment for the progressive damage analysis of composite structures. The accuracy and efficiency of the proposed computational platform are assessed via comparison against the traditional approaches as well as experimental results found in the literature

Porosity analysis in SiC/SiC ceramic matrix composites

Ceramic matrix composites made of silicon carbide fibers embedded in silicon carbide matrix (SiC/SiC CMCs) are widely recognized as excellent replacements for denser superalloys such as Nickel based super alloys for high-temperature applications in aero engines. During the manufacturing process with chemical vapour infiltration, large amount of pores are introduced in the CMC and their presence can have considerable impact on the structural performance of a component. In this work, we analyze the pore size and spatial distribution in SiC/SiC CMCs for different geometrically-identical specimens. Porosity within specimens are quantified through computed tomography (CT) scans. Different statistical approaches are utilized for describing the amount of pores, their size and spatial distribution within each specimen

Computationally-efficient Structural Models for Analysis of Woven Composites

The paper presents a novel approach to model woven composite using the computationally efficient one-dimensional models. The framework is built within the scheme of the Carrera Unified Formulation (CUF), a generalized hierarchical formulation that generates variable kinematic structural theories. Various components of the woven composite unit cell are modeled using a combination of straight and curved one-dimensional CUF models. By employing a component-wise approach, a modeling technique within CUF, the complex geometry of the woven composite components is modeled precisely. The ability of CUF models to accurately resolve stress and strain fields are exploited to capture complex deformation within a woven composite unit cell. Numerical results include analyses of a non-crimped textile composite, a curved tow under tension, and a dry woven textile unit cell

Polyethylene/Polyhydroxyalkanoates-based Biocomposites and Bionanocomposites

The development of advanced polymer composite materials having superior mechanical properties has opened up new horizons in the field of science and engineering. Polyethylene (PE) is considered one of the most widely used thermoplastics in the world due to its excellent properties which have excellent chemical inertness, low coefficient of friction, toughness, near-zero moisture absorption, ease of processing and electrical properties. Polyhydroxyalkanoates (PHAs) are garnering increasing attention in the biodegradable polymer market because of their promising properties such as high biodegradability in different environments. This chapter covers polyethylene/polyhydroxyalkanoates-based biocomposites and bionanocomposites. It summarizes many of the recent research accomplishments in the area of PE/PHAs-based biocomposites and bionanocomposites such as state-of-the-art regarding different methods of their preparation. Also discussed are different characterization techniques and use of PE/PHAs-based biocomposites and bionanocomposites in biomedical, packaging, structural, military, coating, fire retardant, aerospace and optical applications, along with recycling and lifetime studies

Progressive Damage Analysis of Composite Structures via The one-dimensional Carrera Unified Formulation

This paper presents a progressive damage model of composite structures based on refined one-dimensional models. The damage model is implemented in conjunction with the Carrera Unified Formulation (CUF). In the CUF framework, the governing equations and finite element matrices are given via a few fundamental expressions, namely the fundamental nuclei, which are independent of the order of the structural model. The 1D models are built using expansions of the displacement field above the cross-section. Within the CUF framework, the Component-Wise refined beams are used to model every component of an engineering structure via Lagrange Expansion (LE) elements independently of their geometry, e.g. 2D transverse stiffeners and panels, and of their scale, e.g. fibre/matrix cells. The CUF allows the use of any order 1D structural models in a unified manner. A three-dimensional orthotropic elastic constitutive model with continuum damage based degradation is implemented. A stress-based failure envelope is predicted using Hashin’s criteria for uni-directional composites. The progression of damage is controlled by a linear damage evolution law and is based on fracture energy dissipation. A Newton-Raphson based iterative scheme is used to solve the non-linear problem. Damage propagation in laminated composite structures is obtained using highly accurate 3D displacement, strain, and stress fields given by 1D CUF