Fracture toughness

About: Fracture toughness is a research topic. Over the lifetime, 39642 publications have been published within this topic receiving 854338 citations.

Nonlinear Fracture Mechanics for Engineers

Abstract: Overview Introduction Classification of Fracture Mechanics Regimes History of Developments in Fracture Mechanics Review of Solid Mechanics Stress Strain Elasticity Plasticity Consideration of Creep Component Analysis in the Plastic Regime Fully Plastic/Limit Loads Review of Linear Elastic Fracture Mechanics Basic Concepts Crack Tip Plasticity Compliance Relationships Fracture Toughness and Predictive Fracture in Components Subcritical Crack Growth Limitations of LEFM Analysis of Cracks under Elastic-Plastic Conditions Introduction Rice's J-Integral J-Integral, Crack Tip Stress Fields, and Crack Tip Opening Displacement J-Integral as a Fracture Parameter and Its Limitations Methods of Estimating J-Integral Analytical Solutions J-Integral for Test Specimens J for Growing Cracks Numerically Obtained Solutions Tables of J-Solutions Crack Growth Resistance Curves Fracture Parameters under Elastic-Plastic Loading Experimental Methods for Determining Stable Crack Growth and Fracture Special Considerations for Weldments Instability, Dynamic Fracture, and Crack Arrest Fracture Instability Fracture under Dynamic Conditions Crack Arrest Test Methods for Dynamic Fracture and Crack Arrest Constraint Effects and Microscopic Aspects of Fracture Higher Order Terms of Asymptotic Series Cleavage Fracture Ductile Fracture Ductile-Brittle Transition Fatigue Crack Growth under Large-Scale Plasticity Crack Tip Cyclic Plasticity, Damage, and Crack Closure ?J-Integral Test Methods for Characterizing FCGR under Large Plasticity Conditions Behavior of Small Cracks Analysis of Cracks in Creeping Materials Stress Analysis of Cracks Under Steady-State Creep Analysis of Cracks under Small-Scale and Transition Creep Consideration of Primary Creep Effects of Crack Growth on the Crack Tip Stress Fields Crack Growth in Creep-Brittle Materials Creep Crack Growth Test Methods for Characterizing Creep Crack Growth Microscopic Aspects of Creep Crack Growth Creep Crack Growth in Weldments Creep-Fatigue Crack Growth Early Approaches for Characterizing Creep-Fatigue Crack Growth Behavior Time-Dependent Fracture Mechanics Parameters for Creep-Fatigue Crack Growth Methods of Determining (Ct)avg Experimental Methods for Characterizing Creep Crack Growth Creep-Fatigue Crack Growth Correlations Case Studies Applications of Fracture Mechanics Fracture Mechanics Analysis Methodology Case Studies Appendices Index

Quasi-static crack propagation

Abstract: When cracks of any size spread in brittle materials and when large cracks spread in large structures of ductile materials, irreversible deformation is confined to a small volume of material contiguous with the crack surfaces. A general theory of quasi-static crack propagation under such conditions is formulated. The stability of crack propagation is subject to chosen constraints, and general stability criteria under monotonically increasing load and displacement are presented. Experiments in which cracks are spread quasi-statically are described, and by recording both load and corresponding displacement of load, the local specific work of crack spreading, or fracture toughness ( R ) may be deduced without calculation of the elastic stress distribution or even measuring the shape of the test piece. By causing the crack to spread at a range of speeds, variation of R with speed of crack front may be found. When R is independent of scale, it is shown that the stress intensity to propagate geometrically similar cracks in geometrically similar structures varies inversely as the square root of the size. A principle controlling the path of a quasi-static crack is proposed and some experimental confirmation is offered. An interpretation of crack spreading under cyclic loading is given.

Load-adaptive crystalline–amorphous nanocomposites

Abstract: Advances in laser-assisted deposition have enabled the production of hard composites consisting of nanocrystalline and amorphous materials Deposition conditions were selected to produce super-tough coatings, where controlled formation of dislocations, nanocracks and microcracks was permitted as stresses exceeded the elastic limit This produced a self-adjustment in the composite deformation from hard elastic to quasiplastic, depending on the applied stress, which provided coating compliance and eliminated catastrophic failure typical of hard and brittle materials The load-adaptive concept was used to design super-tough coatings consisting of nanocrystalline (10–50 nm) TiC grains embedded in an amorphous carbon matrix (about 30 vol%) They were deposited at near room temperature on steel surfaces and studied using X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, Raman spectroscopy, nanoindentation and scratch tests Design concepts were verified using composition–structure–property investigations in the TiC–amorphous carbon (a-C) system A fourfold increase in the toughness of hard (32 GPa) TiC–a-C composites was achieved in comparison with nanocrystalline single-phase TiC

Influence of Annealing on Microstructure and Mechanical Properties of Isotactic Polypropylene with β-Phase Nucleating Agent

Abstract: The microstructure and mechanical properties of β-nucleated iPP before and after being annealed at different temperatures (90−160 °C) have been analyzed. Annealing induced different degrees of variation in fracture toughness of β-nucleated iPP samples, namely, slight enhancement at relatively low annealing temperatures ( 140 °C) has been observed. The variation of fracture toughness of β-nucleated iPP is observed to be dependent on the content of β-NA. Experiments, including scanning electronic microscope (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and dynamic mechanical analysis (DMA), are performed to study the variations of microstructures as well as the toughening mechanism of the β-nucleated iPP after being annealed. The results indicate that the decreased number of chain segments in the amor...

Temperature effects in the fracture of PMMA

Abstract: Experiments are described in which the fracture toughness,K c, of PMMA has been determined in the temperature range −190 to + 80° C and over the crack speed range of 10−2 to 102 mm sec−1. Single edge notch tension was used for instability measurements but the other data were obtained using the double torsion method. In the range −80 to + 80°C the variations inK c may be described in terms of modulus changes and a constant crack opening displacement criterion. Crack instabilities are correlated with isothermal-adiabatic transitions at the crack tip. Below −80° C there is an inverted rate dependence associated with thermal effects during post-instability crack propagation.