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Cohesive Zone Model
The cohesive zone model (CZM) is a model in fracture mechanics Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics t ... where fracture formation is regarded as a gradual phenomenon and separation of the crack surfaces takes place across an extended crack tip, or cohesive zone, and is resisted by cohesive tractions. The origin of this model can be traced back to the early sixties by Dugdale (1960) and Barenblatt (1962) to represent nonlinear processes located at the front of a pre-existent crack. Description The major advantages of the CZM over the conventional methods in fracture mechanics like those including LEFM (Linear Elastic Fracture Mechanics), CTOD (Crack Tip open Displacement) are: *It is able to adequately predict the behaviour of uncracked structures, including those wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cohesive Zone Fracture Model
Cohesion may refer to: * Cohesion (chemistry), the intermolecular attraction between like-molecules * Cohesion (computer science), a measure of how well the lines of source code within a module work together * Cohesion (geology), the part of shear strength that is independent of the normal effective stress in mass movements * Cohesion (linguistics), the linguistic elements that make a discourse semantically coherent * Cohesion (social policy), the bonds between members of a community or society and life * ''Cohesion'' (album), the fourth studio album by Australian band Gyroscope * Cohesion (band), a musical group from Surrey, England See also * Community cohesion * Structural cohesion * Cohesion number * Adhesion (other) Adhesion is the tendency of certain dissimilar molecules to cling together. Adhesion may also refer to: Biology * Adhesion (medicine), a fibrous band that forms between tissues and organs * Cell adhesion, the binding of a cell to another cell ... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Mechanics
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture. Theoretically, the stress ahead of a sharp crack tip becomes infinite and cannot be used to describe the state around a crack. Fracture mechanics is used to characterise the loads on a crack, typically using a single parameter to describe the complete loading state at the crack tip. A number of different parameters have been developed. When the plastic zone at the tip of the crack is small relative to the crack length the stress state at the crack tip is the result of elastic forces within the material and is termed linear elastic fracture mechanics (LEFM) and can be characterised using the stress intensity factor K. Although the load on a crack can be arbitrary, in 1957 G. Irwin foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Mechanics
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture. Theoretically, the stress ahead of a sharp crack tip becomes infinite and cannot be used to describe the state around a crack. Fracture mechanics is used to characterise the loads on a crack, typically using a single parameter to describe the complete loading state at the crack tip. A number of different parameters have been developed. When the plastic zone at the tip of the crack is small relative to the crack length the stress state at the crack tip is the result of elastic forces within the material and is termed linear elastic fracture mechanics (LEFM) and can be characterised using the stress intensity factor K. Although the load on a crack can be arbitrary, in 1957 G. Irwin foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crack Tip Opening Displacement
Crack tip opening displacement (CTOD) or \delta_\text is the distance between the opposite faces of a crack tip at the 90° intercept position. The position behind the crack tip at which the distance is measured is arbitrary but commonly used is the point where two 45° lines, starting at the crack tip, intersect the crack faces. The parameter is used in fracture mechanics to characterize the loading on a crack and can be related to other crack tip loading parameters such as the stress intensity factor K and the elastic-plastic J-integral. For plane stress conditions, the CTOD can be written as: \delta_\text = \left(\frac\right)\ln\left sec\left(\frac\right)\right/math> where \sigma_\text is the yield stress, a is the crack length, E is the Young's modulus , and \sigma^\infty is the remote applied stress. Under fatigue loading, the range of movement of the crack tip during a loading cycle \Delta\delta_\text can be used for determining the rate of fatigue growth using a crack gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brittleness
A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a sharp snapping sound. When used in materials science, it is generally applied to materials that fail when there is little or no plastic deformation before failure. One proof is to match the broken halves, which should fit exactly since no plastic deformation has occurred. Brittleness in different materials Polymers Mechanical characteristics of polymers can be sensitive to temperature changes near room temperatures. For example, poly(methyl methacrylate) is extremely brittle at temperature 4˚C, but experiences increased ductility with increased temperature. Amorphous polymers are polymers that can behave differently at different temperatures. They may behave like a glass at low temperatures (the glassy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Strength Of A Solid
The theoretical strength of a solid is the maximum possible stress a perfect solid can withstand. It is often much higher than what current real materials can achieve. The lowered fracture stress is due to defects, such as interior or surface cracks. One of the goals for the study of mechanical properties of materials is to design and fabricate materials exhibiting strength close to the theoretical limit. Definition When a solid is in tension, its atomic bonds stretch, elastically. Once a critical strain is reached, all the atomic bonds on the fracture plane rupture and the material fails mechanically. The stress at which the solid fractures is the theoretical strength, often denoted as \sigma_. After fracture, the stretched atomic bonds return to their initial state, except that two surfaces have formed. The theoretical strength is often approximated as: :\sigma_ \cong \frac where *\sigma_ is the maximum theoretical stress the solid can withstand. * E is the Young's Modulus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
