Mechanical property measurement toughness

It is clear that structure-sensitive dynamic properties [low-cycle fatigue (LCF) and fracture toughness (Klc)] notably increase for the alloy with the nondendritic structure. One more proof of the advantage of the nondendritic structure are the results on mechanical properties measured in three directions of forgings from a 1933 grade alloy obtained from large-scale ingots of 845 mm in diameter (Table 16). 

Micro-mechanical properties were determined for the QllOO coating and the uncoated steel substrate using a Fischerscope HIOOC microhardness indenter. Measurements were taken on mounted polished cross-section coupons. Several regions within the coating were surveyed. A fracture toughness value was determined for the coating using a hardness indentation approach [12, 13]. The indentation test conditions and mechanical properties measured are shown in Table 25.2. 

PAEO s 5a and 5c were compression molded at 285 °C to yield tough, transparent films. The mechanical property measurements for 5a and 5c are shown in Table 1. PAEO s 5a and 5c have elongations of 50% or greater. This was unexpected since the PAEO s previously reported by Hergenrother (5) exhibited elongations of less than 10%. 

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-... 

The phenomenological ordering of polymers projected for use as constructing materials is not an easy matter. Sometimes the temperature stability is used as a criterion, i.e., the temperature up to which the mechanical properties remain more or less constant. Another attempt for classification, uses the E modulus or the shape of the curve of stress-strain measurements (see Sect. 2.3.5.1). In general one can say that semicrystalline thermoplastics are stiff, tough, and impact-resistant while amorphous thermoplastics tend to be brittle. Their E... 

As can be seen from the results, the composite formed from monomer/-polymer 114a with Celion G30-500 8HS fabric exhibited excellent mechanical properties [28], To a first approximation it would appear that the inherent fracture toughness of the matrix resin has been carried over to the composite panels. The CAI (compressive strength after impact) and OHC (open hole compression) tests are a direct measurements of the toughness of the composite part, the value of 332 MPa for the CAI compares very favorably to the value of 300 MPa typical for the thermoplastic composites. The OHC values under hot-wet test conditions would seem to indicate that the composite has very good retention of its mechanical properties at both 177°C and 203 °C. 

Mechanical Properties. Because PVDC is difficult to fabricate into suitable test specimens, very few direct measurements of its mechanical properties have been made. Some characteristic properties of high VDC content, unplaslicized copolymers are listed in Table 3. The performance of a given specimen is sensitive to morphology, including the amount and kind of crystallinity, as well as orientation. Tensile strength increases willi crystallinity, whereas toughness and elongation decrease. Orientation, however, improves all three properties. 

Mechanical Properties of Cast Resins. The toughness of the cross-linked polymers was determined by the area under the stress-strain curve and by the energy required to fracture. The fracture or impact energy, expressed in inch-pounds, was measured by a simple but reliable test— the Gardner impact—which consists of striking cured specimens with a 2-lb round-nose rod, %-inch in diameter, from various distances the test specimens were discs 0.1 inch thick by 2.0 inches in diameter. 

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