scholarly journals Fatigue Damage in Cross-Ply Titanium Metal Matrix Composites Containing Center Holes

1993 ◽  
Vol 115 (4) ◽  
pp. 404-410 ◽  
Author(s):  
J. G. Bakuckas ◽  
W. S. Johnson ◽  
C. A. Bigelow
Keyword(s):  
Fatigue Damage ◽  
Effective Strain ◽  
Three Dimensional ◽  
Fatigue Loading ◽  
Matrix Composites ◽  
Element Analysis ◽  
Damage Initiation ◽  
Matrix Cracks ◽  
The Matrix ◽  
Notched Strength

The development of fatigue damage in four [0/90]s SCS-6/Ti-15-3 laminates containing center holes was investigated. A methodology to predict damage initiation based on an effective strain parameter was used to determine the stress levels and the number of cycles required for matrix crack initiation. Damage progression was monitored at various stages of fatigue loading. In general, a saturated state of damage consisting of matrix cracks and fiber-matrix debonding was obtained which reduced the composite modulus. Matrix cracks were bridged by the 0° fibers. The fatigue limit (stress causing catastrophic fracture of the laminates) was also determined. The static and post-fatigue residual strengths were accurately predicted using a three dimensional elastic-plastic finite element analysis. The matrix damage that occurred during fatigue loading significantly reduced the notched strength.

Matrix cracking and the mechanical behaviour of SiC─CAS composites

1992 ◽  
Vol 437 (1899) ◽  
pp. 109-131 ◽  
Keyword(s):  
Elastic Properties ◽  
Three Dimensional ◽  
Matrix Cracking ◽  
Repeated Loading ◽  
Matrix Composites ◽  
Pull Out ◽  
Matrix Cracks ◽  
Brittle Matrix Composites ◽  
Dimensional Network ◽  
The Matrix

An experimental investigation has been carried out on the mechanical properties of unidirectional (0) 12 , (0, 90) 3S , (±45, 0 2 ) S , and (±45) 3S composites consisting of CAS glass ceramic reinforced with Nicalon SiC fibres. Measurements have been made of the elastic properties and of the tensile, compression and shear strengths of the composites, and these have been supported by a detailed study of the damage which occurs during monotonic and repeated loading. These damage studies have been carried out by means of edge replication microscopy and acoustic emission monitoring. The elastic properties of the composites are, by and large, close to the values that would be predicted from the constituent properties and lay-up sequences, but their strengths are lower than expected, and it appears that the Nicalon reinforcing fibre has been seriously degraded during manufacture. The fracture energy is much higher than predicted from observations of fibre pull-out, and it is suggested that the energy required to form a close three-dimensional network of matrix cracks could account for the high apparent toughness. The matrix cracking stress can be predicted reasonably closely by the Aveston, Cooper and Kelly model of cracking in brittle matrix composites, but it is shown that subcritical microcracks can form and/or grow at stresses well below the predicted critical values without affecting composite properties.

Damage Initiation and Evolution in Woven Composites

2001 ◽  
Author(s):  
Xiaodong Tang ◽  
John D. Whitcomb
Keyword(s):  
Three Dimensional ◽  
Woven Composites ◽  
Element Analysis ◽  
Damage Initiation ◽  
Loss And Damage ◽  
Dimensional Finite Element ◽  
Strain Relationship ◽  
Three Dimensional Finite Element ◽  
Stiffness Loss ◽  
Damage Initiation And Evolution

Abstract The damage initiation and evolution mechanisms in plain and satin weave composites were studied using three-dimensional finite element analysis. The tow paths of the weave were selected such that the wavy region of the tows were identical in both weaves. The damage initiation and evolution behaviors in these comparable wavy regions were compared and discussed in terms of stress components that initiate damage, the overall stress/strain relationship and the accumulation of the damaged volume in the warp tow, fill tow and matrix pockets. The results showed significant similarities in many aspects of the damage behaviors such as damage modes, stiffness loss and damage accumulation processes.

Compressive Deformation of Hollow Microsphere Reinforced Metal Matrix Composites

1994 ◽  
Vol 372 ◽  
Author(s):  
M. T. Kiser ◽  
M. He ◽  
B. Wuj ◽  
F. W. Zok
Keyword(s):  
Aluminum Matrix ◽  
Hollow Microsphere ◽  
Compressive Deformation ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Element Analysis ◽  
Strength Enhancement ◽  
The Matrix ◽  
Matrix Flow ◽  
Measured Strength

AbstractThe compressive deformation characteristics of hollow alumina microsphere reinforced aluminum matrix composites have been studied through both experiments and finite element analysis of unit cell models. Tests have been performed on composites containing around 50 volume percent of microspheres. The effects of the matrix flow stress and microsphere morphology (characterized by the ratio of wall thickness to radius) have been examined. The measured strength enhancement due to the hollow microspheres was found to be considerably less than that predicted by the FEM calculations; a result of microsphere cracking. Experiments have been conducted to document the progression of such damage following casting and mechanical deformation. The potential of this class of composite for impact energy absorption applications is also explored.

scholarly journals Research on a 3-DOF Motion Device Based on the Flexible Mechanism Driven by the Piezoelectric Actuators

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 578 ◽  
Author(s):  
Bingrui Lv ◽  
Guilian Wang ◽  
Bin Li ◽  
Haibo Zhou ◽  
Yahui Hu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Machining Process ◽  
Element Analysis ◽  
3D Motion ◽  
Compliance Modeling ◽  
The Matrix ◽  
Static Performance ◽  
Flexible Mechanism

This paper describes the innovative design of a three-dimensional (3D) motion device based on a flexible mechanism, which is used primarily to produce accurate and fast micro-displacement. For example, the rapid contact and separation of the tool and the workpiece are realized by the operation of the 3D motion device in the machining process. This paper mainly concerns the device performance. A theoretical model for the static performance of the device was established using the matrix-based compliance modeling (MCM) method, and the static characteristics of the device were numerically simulated by finite element analysis (FEA). The Lagrangian principle and the finite element analysis method for device dynamics are used for prediction to obtain the natural frequency of the device. Under no-load conditions, the dynamic response performance and linear motion performance of the three directions were tested and analyzed with different input signals, and three sets of vibration trajectories were obtained. Finally, the scratching experiment was carried out. The detection of the workpiece reveals a pronounced periodic texture on the surface, which verifies that the vibration device can generate an ideal 3D vibration trajectory.

scholarly journals COMPUTATIONAL MICROSTRUCTURE-BASED ANALYSIS OF RESIDUAL STRESS EVOLUTION IN METAL-MATRIX COMPOSITE MATERIALS DURING THERMOMECHANICAL LOADING

2021 ◽  
Vol 19 (2) ◽  
pp. 241
Author(s):  
Ruslan Balokhonov ◽  
Varvara Romanova ◽  
Eugen Schwab ◽  
Aleksandr Zemlianov ◽  
Eugene Evtushenko
Keyword(s):  
Residual Stress ◽  
Metal Matrix ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Matrix Composites ◽  
Two Phase ◽  
Irregular Shapes ◽  
The Matrix ◽  
Stress Formation ◽  
Mechanical Fragmentation

A technique for computer simulation of three-dimensional structures of materials with reinforcing particles of complex irregular shapes observed in the experiments is proposed, which assumes scale invariance of the natural mechanical fragmentation. Two-phase structures of metal-matrix composites and coatings of different spatial scales are created, with the particles randomly distributed over the matrix and coating computational domains. Using the titanium carbide reinforcing particle embedded into the aluminum as an example, plastic strain localization and residual stress formation along the matrix-particle interface are numerically investigated during cooling followed by compression or tension of the composite. A detailed analysis is performed to evaluate the residual stress concentration in local regions of bulk tension formed under all-round and uniaxial compression of the composite due to the concave and convex interfacial asperities.

Substrate Damage Modeling for Advanced Turbine System Airfoils

2009 ◽  
Author(s):  
Ventzislav G. Karaivanov ◽  
Sean Siw ◽  
Minking K. Chyu ◽  
William S. Slaughter ◽  
Mary Anne Alvin
Keyword(s):  
Fatigue Damage ◽  
Damage Mechanics ◽  
Three Dimensional ◽  
Department Of Energy ◽  
Internal Cooling ◽  
Element Analysis ◽  
Service Operation ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Damage Simulation

The Department of Energy (DOE) is developing advanced hydrogen-fired and oxy-fueled turbine technologies that are projected to operate with turbine inlet temperatures (TIT) of 1425°C and 1760°C, respectively. At these temperatures, the airfoil will require not only internal cooling, but also stable thermal barrier coatings (TBCs) in order to achieve extended service operation in these advanced high steam-containing environments. We previously developed a computational methodology, based on three-dimensional finite element analysis (FEA) and damage mechanics, for predicting the evolution of creep in the hydrogen-fired and oxy-fueled airfoils. This methodology has been extended to fatigue damage evolution. Currently, the model allows for the interaction between creep and fatigue damage. Simulation results will be presented that visualize creep and fatigue damage for hydrogen-fired and oxy-fuel airfoils. Additionally, the influence of dynamic changes in the TBC microstructure and phase composition with operational time will be discussed relative to all projected damage mechanisms.

Load Spectrum Compiling and Practical Application of Output Flange for Wheel Loader Gearbox

2011 ◽  
Vol 346 ◽  
pp. 483-489
Author(s):  
Ying Shuang Zhang ◽  
Guo Qiang Wang ◽  
Ji Xin Wang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Prediction Method ◽  
Fatigue Loading ◽  
Load Spectrum ◽  
Element Analysis ◽  
Wheel Loader ◽  
Program Load Spectrum ◽  
Program Load

To realize the structural light weighting design of the transmission components of engineering vehicles on the basis of life in control, this paper took wheel loader as an example, collected the time-domain load signals of the transmission system in typical working conditions, provided processing steps for load spectrum synthesis by a certain percentage, and generated the program load spectrum which consisted of various amplitudes and means. The load spectrum can be used for fatigue loading at the output flange of gearbox. Then, the finite element model of the flange was established, and the stress analysis was carried out in the stress concentration location such as fillet. The prediction method of fatigue life on the base of program load spectrum was given. After the fatigue life prediction based on the compiled load spectrum and the theory of cumulative fatigue damage, the fatigue life of outside fillet of the flange, where is of maximum stress, is obtained. It was possible to obtain adequately fatigue prediction results in engineering vehicle design, using load spectrum, finite element analysis, and a stress-life approach to fatigue damage calculations.

Application of a Cold ECAP to Magnesium Alloy (AZ31) by a Combination of Extrusion Process

2005 ◽  
Vol 486-487 ◽  
pp. 313-316 ◽  
Author(s):  
Jae Wan Song ◽  
Hee Taek Lim ◽  
Jeong Whan Han ◽  
Mok Soon Kim ◽  
Sun Keun Hwang
Keyword(s):  
Effective Strain ◽  
Three Dimensional ◽  
Az31 Alloy ◽  
Extrusion Process ◽  
New Combination ◽  
Compressive Yield Strength ◽  
Element Analysis ◽  
Combination Process ◽  
Angular Pressing ◽  
Von Mises

It is well known that magnesium alloys have difficulties in room temperature formability because of their HCP structure. As a basic approach to enhance a cold formability, a new combination process including an extrusion followed by a cold equal channel angular pressing (ECAP) was attempted. ECAP die has an inner die corner angle of 135 degree, the fillet angle of 45 degree and thickness of 5mm. A finite element analysis with a three-dimensional thermo-coupled elasto-plastic model was also carried out to understand the change of stress and strain during ECAP. Experiments showed that the AZ31 alloy, which is extruded at a ratio of 20 and is heat-treated at 350°C, was successful in a cold ECAP. From the simulated results, it was found that the effective strain gradually decreased from the inner die side (0.533) to the outer die side. This was confirmed by the analytical analysis via von Mises criterion. Furthermore, it also matched well with the experiments, which showed a uniform shear deformation band. It was also interesting to note that compressive yield strength was drastically increased, which is caused by the occurrence of numerous twins spread across the materials during a cold ECAP.

Effect of Microporosity on Damage Initiation in Ceramic Matrix Composites

2019 ◽  
Author(s):  
Suhasini Gururaja ◽  
Abhilash Nagaraja
Keyword(s):  
Gas Turbines ◽  
Ceramic Matrix Composites ◽  
Local Stress ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Damage Initiation ◽  
The Matrix ◽  
Homogenization Approach ◽  
Matrix Porosity ◽  
Monolithic Ceramics

Abstract Ceramic matrix composites (CMC) are a subclass of composite materials consisting of reinforced ceramics. They retain the advantages of ceramics such as lower density and better refractory properties but exhibit better damage tolerance compared to monolithic ceramics. This combination of properties make CMCs an ideal candidate for use in high temperature sections of gas turbines. However, modeling the damage mechanisms in CMCs is complex due to the heterogeneous microstructure and the presence of processing induced defects such as matrix porosity. The effect of matrix pore location and orientation on damage initiation in CMCs is of interest in the present work. CMCs fabricated by various fabrication processes exhibit matrix pores at different length scales. Microporosities exist within fiber bundles in CMCs have a significant effect on microscale damage initiation and forms the focus of the current study. In a previous work by the authors, a two step numerical homogenization approach has been developed to model statistical distribution of matrix pores and to obtain the effective mechanical properties of CMCs in the presence of matrix porosity. A variation of that approach has been adopted to model matrix pores and investigate the severity of pores with respect to their location and orientation. CMC microstructure at the microscale has been modeled as a repeating unit cell (RUC) consisting of fiber, interphase and matrix. Ellipsoidal pores are modeled in the matrix with pore distance from the interphase-matrix interface and pore orientation with respect to the loading direction as parameters. Periodic boundary conditions (PBCs) are specified on the RUC by means of constraint equations. The effect of the pore on the local stress fields and its contribution to matrix damage is studied.

FE Modeling of FRP-Concrete Interface for very High Cycle Fatigue Behavior

2013 ◽  
Vol 577-578 ◽  
pp. 165-168 ◽  
Author(s):  
M. Mahal ◽  
T. Blanksvärd ◽  
B. Täljsten
Keyword(s):  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Finite Element Program ◽  
Element Program ◽  
Three Dimensional Finite Element ◽  
Concrete Interface

The fatigue damage of FRP-concrete interface is a major problem in strengthened structures subjected to fatigue loading. The available FRP-concrete interface models published in the literature usually deal with fracture mechanism approach, which is unsuitable for high cycle fatigue damage. In this study, a constitutive micro model is developed for FRP-concrete interface for high cycle fatigue and incorporated into a three dimensional finite-element program. Numerical analysis of a double lap joint is carried out, and the results show that the proposed model is reasonably accurate.

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