Mechanical properties fracture toughness

Lac Each, R., Schone, J., Bierogel, C., Grellmann, W. Instrumented macroindentation techniques for polymers and composites - Mechanical properties, fracture toughness and time - dependent behaviour as a function of the temperature. Macromol. Symp. 315 (2012) 125-131. 

Ma Ma, J., Mo, M.-S., Du, X.-S., Rosso, P., Friedrich, K., Kuan, H.-C. Effect of inorganic nanoparticles on mechanical property, fracture toughness and toughening mechanism of two epoxy systems. Polymer 49 (2008) 3510-3523. 

Abstract The effects of three degrees of cure (low, standard and postcured) on two carbon reinforced epoxy resins are examined. The polymerization degree is tentatively assessed by thermal antdysis techniques, namely by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The effects on both static mechanical and fracture toughness properties have been checked. It has been found that the glass transition temperature measured by DMA is the parameter, among those studied (both thermal and mechanical), that is more sensitive to the cure degrees. 

The static mechanical and fracture toughness tests have been selected to highlight the resin dependent properties. 

R.E. Davies, G.E. Nordmark, and J.D. Walsh, Design Mechanical Propoties, Fracture Toughness, Fatigue Properties Exfoliation and Stress Corrosion Resistance of 7050 Sheet, Plate, Extrusions, Hand Forgings and Die Forgings, Final Report, Naval Air Systems, Contract N00019-72-C-0512, July 1975... 

Finally, the nature of the crystalline microstmcture, ie, crystal size and morphology and the textural relationship among the crystals and glass, is the key to many mechanical and optical properties, including transparency/opacity, strength and fracture toughness, and machinabiUty. These microstmctures can be quite complex and often are distinct from conventional ceramic microstmctures (6). 

Film Adhesion. The adhesion of an inorganic thin film to a surface depends on the deformation and fracture modes associated with the failure (4). The strength of the adhesion depends on the mechanical properties of the substrate surface, fracture toughness of the interfacial material, and the appHed stress. Adhesion failure can occur owiag to mechanical stressing, corrosion, or diffusion of interfacial species away from the interface. The failure can be exacerbated by residual stresses in the film, a low fracture toughness of the interfacial material, or the chemical and thermal environment or species in the substrate, such as gases, that can diffuse to the interface. 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quaUty. Standard test methods employed by the iadustry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeabiUty, microstmcture, Poisson s ratio, transverse mpture strength, and Young s modulus are set forth by ASTM/ANSI and the ISO. 

The measurement of mechanical properties is a major part of the domain of characterisation. The tensile test is the key procedure, and this in turn is linked with the various tests to measure fracture toughness... crudely speaking, the capacity to withstand the weakening effects of defects. Elaborate test procedures have been developed to examine resistance to high-speed impact of projectiles, a property of civil (birdstrike on aircraft) as well as military importance. Another kind of lest is needed to measure the elastic moduli in different directions of an anisotropic crystal this is, for instance, vital for the proper exploitation of quartz crystal slices in quartz watches. 

In the matrix of PLA/ polycaprilactone (PCL)/OMMT nano-composites, the silicate layers of the organoclay were intercalated and randomly distributed (Zhenyang et at, 2007). The PLA/PCL blend significantly improved the tensile and other mechanical properties by addition of OMMT. Thermal stability of PLA/PCL blends was also explicitly improved when the OMMT content is less than 5%wt. Preparation of PLA/thermoplastic starch/MMT nano-composites have been investigated and the products have been characterized using X-Ray diffraction, transmission electron microscopy and tensile measurements. The results show improvement in the tensile and modulus, and reduction in fracture toughness (Arroyo et ah, 2010). 

Since the early 1980s, the study of mechanical properties of materials on the nanometre scale has received much attention, as these properties are size dependent. The nanoindentation and nanoscratch are the important techniques for probing mechanical properties of materials in small volumes. Indentation load-displacement data contain a wealth of information. From the load-displacement data, many mechanical properties such as hardness and elastic modulus can be determined. The nanoindenter has also been used to measure the fracture toughness and fatigue properties of ul-... 

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