Ductile fracture mode

For this semi-ductile fracture mode, a method using two material parameters has been proposed to characterize the impact resistance of the polymer [11], The method takes account of an average value of the fracture energy during the stable propagation of the crack, and also the fracture energy at instability. In this case, the total energy absorbed by the sample to break, U, has been shown... 

It is seen that titanium alloyed with boron and silicon is promising owing to high strength and Young modulus, and has high ductile potential because fails with ductile fracture mode. As to the structural and fractographical features of the alloys studied they are as follows ... 

Simple fracture is the separation of a body into two or more pieces in response to an imposed stress that is static (i.e., constant or slowly changing with time) and at temperatures that are low relative to the melting temperatnre of the material. Fracture can also occur from fatigue (when cyclic stresses are imposed) and creep (time-dependent deformation, normally at elevated temperatnres) the topics of fatigue and creep are covered later in this chapter (Sections 8.7 throngh 8.15). Althongh applied stresses may be tensile, compressive, shear, or torsional (or combinations of these), the present discussion wiU be confined to fractnres that resnlt from uniaxial tensile loads. For metals, two fracture ductile fracture, modes are possible ductile and brittle. Classification is based on the ability of a material... 

Both brittle and ductile fracture modes are possible. 

There are a number of fracture modes, the most important of which are ductile overload, which is fairly well understood and can be predicted reasonably accurately, and brittle fracture, which is less predictable from an engineering viewpoint and can cause catastrophic failures due to the speed of the fracture. 

The early study of brittle failures, notably those of the Liberty ships, indicated a temperature dependence. This can be illustrated by plotting both fracture stress (of) and yield stress (Oy) against temperature (Fig. 8.81). Below a certain temperature some materials exhibit a transition from ductile to brittle fracture mode. This temperature is known as the ductile-brittle transition temperature DBTT. 

Although the creep behavior of a material could be measured in any mode, such experiments are most often run in tension or flexure. In the first, a test specimen is subjected to a constant tensile load and its elongation is measured as a function of time. After a sufficiently long period of time, the specimen will fracture that is a phenomenon called tensile creep failure. In general, the higher the applied tensile stress, the shorter the time and the greater the total strain to specimen failure. Furthermore, as the stress level decreases, the fracture mode changes from ductile to brittle. With flexural, a test specimen... 

B. The direct identification of such microscopic fracture modes as transgranular cleavage, radial fracture, intergranular separation or ductile dimpled rupture, was shown to be considerably more dependable by SEM than by OM... 

The term fracture implies fragmentation of a solid body into two or more bodies under the action of stress. Two main types of fracture mode are observed in solids. The first is ductile fracture which is the failure of a material after it has undergone a considerable amount of plastic deformation. The other is brittle fracture which is the failure of a material without undergoing practically any plastic deformation. The type of failure which occurs depends largely on the nature of the material and its condition however, failure is also affected by... 

Impact modifiers for PET are generally elastomeric compounds that increase impact strength and elongation while usually decreasing modulus. An effective way to enhance the impact strength and to induce a brittle/ductile transition of the fracture mode, is by the dispersion of a rubber phase within the PET matrix. The... 

The failure processes in thermoplastics composites with aligned glass fibers of sub-critical transfer length have been characterized (Lauke and Schultrich, 1983, 1986a, b Lauke et al., 1985 Lauke and Pompe, 1988) in terms of matrix fracture mode which is determined mainly by the ductility of the matrix material, loading rate and temperature. The total specific work of fracture, / t, is expressed as the sum... 

By increase of the temperature the mode of failure is changed from brittle fracture to ductile fracture, characterised by the appearance of a yield point prior to fracture, and sometimes by indications of necking. 

Ni-20Cr 60 ppm Ce 0.90 rate, transition from brittle intergranular to ductile transgranular fracture mode ... 

With increasing temperature, the fracture mode changes from brittle to semi-ductile at about -50 °C and then becomes ductile at temperatures higher than... 

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