Multi-scale Progressive Failure Analysis Research Articles

Multi-scale progressive failure analysis of shear deformed woven fabric composites considering its pre-forming process

Multi-scale progressive failure analysis of shear deformed woven fabric composites considering its pre-forming process

INTEGRATED COMPUTATIONAL MATERIAL SCIENCE ENGINEERING LIFING MODEL OF CMC COUPONS USING NANO-MICROMECHANICS BASED MULTISCALE PROGRESSIVE FAILURE ANALYSIS

The overall objective of this effort was to provide theoretical prediction for damage development for a set of laminated composites using AlphaSTAR Technology Solutions' (ATS's) commercial code GENOA (GENeral Optimization Analyzer) for the Air Force Research Laboratory (AFRL) program entitled "Assessment of Damage Progression Models for SiC/SiC Ceramic Matrix Composites (CMC Lifing Program)." Damage progression and prediction for advance ceramic matrix composite (CMC) benchmarks were done under static, fatigue, and creep service loading using test data from AFRL. Emerging and innovative multiscale (MS) modeling using computational structural mechanics (CSM) and progressive failure analysis (PFA) were proven to address the Air Force's vision to perform predictive evaluation of CMC materials using a building block validation strategy and certification process. Two different material systems and multiple layups were tested for both unnotched and notched configurations and at elevated temperatures. Calibration of the fiber and matrix properties was performed using in plane test data. The static, fatigue, and creep recalibration simulations of strength showed an average error of less than 10% between the simulation and test data. For stiffness the percent difference was found to be within 10% on average as well. All simulations used the same set of inputs (constituents, voids, fiber/matrix interphase, microcrack density, etc.) except for the noted analysis setting differences between blind and recalibration simulations. The method is consistent and follows a building block simulation approach that has an advanced yet simplistic theoretical multiscale progressive failure analysis (MS-PFA) approach.

Prediction of non-linear mechanical behavior of shear deformed twill woven composites based on a multi-scale progressive damage model

In this paper, the non-linear mechanical behavior of shear deformed woven composite was predicted using a representative volume element (RVE) model based on multi-scale progressive failure analysis. The micro-scale RVE model, consisting of single fiber and a matrix, was employed to determine the stress amplification factor and distinguish the failure of each fiber and the matrix constituent. Then, a meso-scale RVE model of shear deformed twill woven composite was developed to predict non-linear behavior using micro-stress transferring with finite element simulation. Fiber yarn shapes were observed with respect to the shear angle of the twill fabric. Based on the observed yarn geometry, shear deformed twill composite was modeled by using the open source software TexGen. To prove validity of the proposed model, shear deformed twill woven composite was fabricated using a picture frame, followed by a vacuum assisted resin transfer molding process. Mechanical tests were conducted and the failure progress during the tests was observed to determine their failure analysis. As a result, a good correlation between the multi-scale progressive damage model and experimental results such as mechanical properties, the non-linear stress-strain curve, and failure modes were achieved.

Damage Tolerance Evaluation of Rotorcraft Horizontal Tail Under Variable Amplitude Service Loading Conditions

To ensure the safe operation of the helicopter throughout its lifetime, the primary structure has to be designed taking into account damage tolerance criteria. This has been considered in the design process, for example, by using multiple load paths as well as by taking into account the presence of certain structural defects like impacts or manufacturing defects in composite parts when performing the dimensioning and lifetime calculations. This paper describes and presents an effort performed for damage tolerance (DT) aspects of rotorcraft horizontal tail (HT) through multi-scale (MS) modeling computational approach to assess the growth rate of damages from fatigue under spectrum loading from rotorcraft mission profile and consideration of the effects of material variability to assess structural advantages. Main emphasis was laid on the design of the cyclic loaded components in order to achieve unlimited life with high flaw tolerance. A micromechanics-based multi-scale progressive failure analysis (MS-PFA) approach that detects damage and fracture evolution is carried out to assess the durability and damage tolerance (DD (2) fiber waviness exhibited in thick sections; and (3) void shape, size, distribution. Fatigue life is estimated under service spectrum block loading conditions in critical mission by determining the material stiffness and strength degradation, failure load and cycles.

Multi-scale Progressive Failure Analysis of Triaxially Braided Textile Composites

Multi-scale Progressive Failure Analysis of Triaxially Braided Textile Composites

An investigation of intelligent tires using multiscale modeling of cord-rubber composites

ABSTRACTA computational model based on the multiscale progressive failure analysis is employed to provide the theoretical predictions for damage development in the cord-rubber composites in tires. Vulcanized rubber, reinforcing belts, and carcass used in tire structures cause the anisotropic behavior under different loading conditions. Steel reinforcement layers made of steel wires combined with rubber complicate the macro-scale finite element modeling of tires. This paper presents a new three-dimensional model of the cord-rubber composite used in tires in order to predict the different types of damage including matrix cracking, delamination, and fiber failure based on the micro-scale analysis. Additionally, intelligent tires have the potential to be widely used to enhance the safety of road transportation systems, and this paper provides an estimation of the effects of void volume fraction, fiber volume fraction, and stacking sequence of the cord-rubber composites on the acceleration profile of the tire measured at the inner-liner.

Damage-tolerant composite design principles for aircraft components under fatigue service loading using multi-scale progressive failure analysis

Virtual testing has lately gained widespread acceptance among scientists as a simple, accurate, and reproducible method to determine the mechanical properties of heterogeneous microstructures, early in the production process. As a result of the rapid expansion of the use of composites in aerospace design, virtual testing techniques are, in fact, deemed extremely useful to eliminate unnecessary tests and to reduce cost and time associated with generating allowables for lengthy lifing analyses of structures. Leveraging on a limited set of experimental data, a Progressive Failure Analysis can accurately predict the life and safety of a component/assembly, simply tapping on the physics of its micro-/macro- mechanics material properties, manufacturing processes, and service environments. The robust methodology is showcased using blind predictions of fatigue stiffness degradation and residual strength in tension and compression after fatigue compared with test data from Lockheed Martin Aeronautics and Air Force Research Laboratory). The multi-scale progressive failure analysis methodology in the GENOA software considers uncertainties and defects and evaluated the damage and fracture evolution of three IM7-977-3 laminated composite layups at room temperature. The onset and growth of composite damage was predicted and compared with X-ray CT. After blind predictions, recalibrations were performed with knowledge of the test data using the same set of inputs for all layups and simulations. Damage and fracture mechanism evolution/tracking throughout the cyclic loading is achieved by an integrated multi-scale progressive failure analysis extended FEM solution: (a) damage tracking predicts percentage contributing translaminar and interlaminar failure type, initiation, propagation, crack growth path, and observed shift in failure modes, and (b) fracture mechanics (VCCT, DCZM) predicts crack growth (Crack Tip Energy Release Rate vs. Crack Length), and delamination. The predictive methodology is verified using a building block validation strategy that uses: (a) composite material characterization and qualification (MCQ) software, and (b) the GENOA multi-scale progressive failure analysis fatigue life, stiffness degradation, and post-fatigue strength predictions for open-hole specimens under tension/compression at RTD. The unidirectional tension, compression, and in-plane shear lamina properties supplied by Lockheed Martin Aeronautics and the Air Force Research Laboratory (based on the D3039, D638, D3518 tests) were used by MCQ to reverse engineer effective fiber and matrix static and fatigue properties for the IM7-977-3 material system. The use of constituent properties identified the root cause problem for composite failure and enabled the detection of damage at the micro-scale of the material where damage is incepted. For all three case studies (namely, layups [0/45/90/−45]2s, [+60, 0, −60]3s, and [+30, +60, 90, −60, −30]2s), the blind predictions on the fatigue stiffness degradation and residual strength of the open-hole coupon in tension/compression under cyclic loading (with R = 0.1) at RTD were evaluated using a FE mesh (made of 2k shell elements), in which only one shell element, containing all plies, was employed through the thickness. The results of all analyses correlated very well with the tests, including the damage micro-graphs generated during the cyclic loading.

Damage tolerant composite design principles for aircraft components under static service loading using multi-scale progressive failure analysis

The overall objective of this effort was to provide theoretical prediction for damage development for a set of laminated composites using Alpha STAR Corporations’ commercial code GENOA (GENeral Optimization Analyzer) for the Air Force Research Laboratory program entitled “Damage Tolerance Design Principles (DTDP)”. Damage progression and prediction for advance composite benchmarks were done under static and fatigue service loading using test data from Lockheed Martin Aeronautics and Air Force Research Laboratory. In the current paper, the results for the static analysis are presented. Emerging and innovative multi-scale (MS) modeling using computational structural mechanics and progressive failure analysis were proven to address the Air Force’s vision to perform predictive evaluation of composite materials using a building block validation strategy and certification process. Three layups were tested in tension and compression for unnotched and openhole configurations. Calibration of the fiber and matrix properties was performed using in plane, 3pt bend and DCB test data. After this, mesh convergence, solver selection based on CPU time, and mesh sensitivities was performed. The static blind simulations of strength showed an average error of 12.9% between simulation and the test data. For stiffness, the percent difference was found to be 23.5% on average. Although the focus was on the ability to blindly predict test data, recalibration efforts show an average of 9.2% difference between simulation and test for strengths and 12.4% for stiffness computations. Damage at ∼60–75% and ∼90% of max loading was comparable with X-ray observations of specimens set aside solely for that purpose. All simulations used the same set of inputs (constituents, voids, fiber waviness, etc.) except for the noted analysis setting differences between blind and recalibration simulations. The method is consistent and follows a building block simulation approach that has an advanced yet simplistic theoretical multi-scale progressive failure analysis approach all contained in the commercial GENOA software. The method was demonstrated to work having GENOA directly run sequential NASTRAN simulations and, post project completion, with the ABAQUS solver using GENOA as a material subroutine.

Micromechanics-based progressive failure analysis prediction for WWFE-III composite coupon test cases

As a part of a world-wide study, a commercial code (General Optimization Analyzer), based on multi-scale (micro–macro) progressive failure analysis (PFA), is used to provide theoretical predictions for damage development for a set of challenging 13 test cases proposed in the Third World-Wide Failure Exercise (WWFE-III). Multiple failure criteria were utilized aimed at tackling issues related to a wide range of damage modes, being addressed by the WWFE-III. The critical damage events/indexes predictions tracked translaminar and interlaminar composite failures, namely matrix cracking/crack density, damage initiation/propagation, delamination initiation/growth, and their interaction with fiber failure. The composite laminates analysed were both with and without a central hole and the predictions were made using constituent fiber properties and matrix properties based on materials data or identification from ply stress–strain curve inputs. Loadings included uniaxial tension or compression, biaxial, bending, thermal, and loading–unloading.

Micromechanical damage modeling and multiscale progressive failure analysis of composite pressure vessel

A multiscale damage model is proposed to predict the failure properties and ultimate burst pressure of composite pressure vessel. The macroscopic damage evolution and stiffness properties of the composite vessel are represented by those of the representative volume element (RVE). First, a microscopic damage model is established, where the fiber breakage is predicted using Monte Carlo simulation, and the progressive matrix cracking is described by continuum damage mechanics-based modeling and the interface failure is simulated using Xu and Needleman’s cohesive model. Then, a stiffness degradation model is proposed to link the macroscopic stiffness of the composite vessel with the failure evolvement of the RVE. Finally, the multiscale progressive failure analysis of the composite vessel is implemented by associating the finite element codes ANSYS-APDL with ABAQUS-UMAT. The numerical convergence problems are effectively addressed by introducing the viscous damping effect. The predicted failure strengths of the composite vessels are consistent with the experimental results.

Recent developments on damage modeling and finite element analysis for composite laminates: A review

Under complex environments such as continuous or cyclic loads, the stiffness degradation for the laminated composites such as the carbon fiber reinforced polymer matrix composites is an important physical and mechanical response to the damage and failure evolution. It is essential to simulate the initial and subsequent evolution process of this kind of damage phenomenon accurately in order to explore the mechanical properties of composite laminates. This paper gives a comprehensive review on the general methodologies on the damage constitutive modeling by continuum damage mechanics (CDM), the various failure criteria, the damage evolution law simulating the stiffness degradation, and the finite element implementation of progressive failure analysis in terms of the mechanical response for the variable-stiffness composite laminates arising from the continuous failure. The damage constitutive modeling is discussed by describing the evolvement of damage tensors and conjugate forces in the CDM theory. The failure criteria which interpret the failure modes and their interaction are compared and some advanced methods such as the cohesive theory which are used to predict the damage evolution properties of composites are also discussed. In addition, the solution algorithm using finite element analysis which implements progressive failure analysis is summarized and several applicable methods which deal with the numerical convergence problem due to singular finite element stiffness matrices are also compared in order to explore the whole failure process and ultimate load-bearing ability of composite laminates. Finally, the multiscale progressive failure analysis as a popular topic which associates the macroscopic with microscopic damage and failure mechanisms is discussed and the extended finite element method as a new finite element technique is expected to accelerate its practical application to the progressive failure analysis of composite laminates.

Multiscale progressive failure analysis of textile composites

The experimental determination of stiffness and strength of textile composites is expensive and time-consuming. Experimental tests are only capable of delivering properties of a whole textile layer, because a decomposition is not possible. However, a textile layer, consisting of several fiber directions, has the drawback that it is likely to exhibit anisotropic material behavior. In the presented paper a finite element multiscale analysis is proposed that is able to predict material behavior of textile composites via virtual tests, solely from the (nonlinear) material behavior of epoxy resin and glass fibers, as well as the textile fiber architecture. With these virtual tests it is possible to make predictions for a single layer within a textile preform or for multiple textile layers at once. The nonlinear and pressure-dependent behavior of the materials covered in the multiscale analysis is modeled with novel material models developed for this purpose. In order to avoid mesh-dependent solutions in the finite-element simulations, regularization techniques are applied. The simulations are compared to experimental test results.