Mechanical property measurement tensile strength

Pharmaceutical tablets are made from a number of components, and each component contributes to the tablet s final properties. Therefore, it is important to study the physical properties of the individual components and their mixture rules in order to predict the mechanical properties of the final tablet. Tensile strength is one of the crucial properties that assess mechanical strength the most common method for measuring tensile strength is the diametrical compression test discussed above (110). In this section the application of the Ryshkewitch-Duckworth equation to the analysis of tensile strength of mixtures will be discussed (151,152). 

This paper presents results from aging polyester based polyurethanes In methanol and water environments and In other mixtures of these media. The Influence of aging on mechanical properties was assessed by measuring tensile strengths and elongations at... 

Mechanical Properties. The tensile properties of the cast specimens were determined using dog-bone-shaped specimens following ASTM D-638, at a crosshead speed of 0.2 in./min on a tensile testing machine (Instron 4505). The strain to failure of the specimens was measured using an exten-someter. The tensile strength and tensile modulus were also determined. 

The superdrawn filaments were very resistant to heat shrinkage, as seen in Figure 3.63. Mechanical property measurements on these filaments after the heat shrinkage showed a 16% loss in modulus and a 10% loss in tensile strength. The fibers began to melt at 155°C, and the peak maximum occurred at 161°C. 

Split cell testers Tensile strength measurements may also evaluate internal adhesion properties, independent of the mechanical interaction of shear plane, because T is measured at zero shear. Warren Springs Laboratories (WSL) designed two instruments one to measure the cohesive strength of powders at varied states of compaction and the other to measure tensile strength. The tensile strength measurement equipment, developed by WSL, was the WSL tensile tester, a diametrically divided split shallow circular cell. 

The latter figure shows the mechanical properties, measured at room temperature, of as-spun poly(l,4-phenylene terephthalamide) fibers plotted against the polymer concentration of the solutions from which the fibers were produced. The draw-down ratio, or spin-stretch factor (wind-up speed/ extrusion rate) was adjusted for each concentration to maintain a constant fiber diameter. Remarkably, these reported results display no discontinuity in the fiber tensile strength or stiffness at the onset of the formation of the anisotropic phase. 

The mechanical properties were investigated in some early studies. In these studies, the creep properties [111], tensile strengths [112], flow stress [113] and high temperature hardness [113,114] of various oxides were measured. The mechanical properties of wustite were also related to scale-steel interface adhesion [115] and marker movement [116] in the wustite scale layer. Based on these early studies, it was concluded that at temperatures above 800°C, wustite was deformable, and even in the range of 650-800°C, wustite still possessed certain plasticity [117], while magnetite and hematite were not deformable even at 1000°C. 

The highest mechanical properties measured on a corrunercial sample of CNS-V were 883 MPa (128 ksi) ultimate tensile strength, 800 MPa (116 ksi) yield strength at 0.2% offset and 29.0 HRC. The measured elongation of this sample is 7.5% and its electrical conductivity is 18 MS/m(31%IACS). 

The most important displacive transformation is the one that happens in carbon steels. If you take a piece of 0.8% carbon steel "off the shelf" and measure its mechanical properties you will find, roughly, the values of hardness, tensile strength and ductility given in Table 8.1. But if you test a piece that has been heated to red heat and then quenched into cold water, you will find a dramatic increase in hardness (4 times or more), and a big decrease in ductility (it is practically zero) (Table 8.1). 

Very recently, Williams, Billington Pearson (1992) have examined the effect of reinforcement by silver or silver-tin alloy on the mechanical properties of three glass-ionomer cements. Measurements of compressive, flexural, tensile (measured by the diametral compressive procedure) and shell strength are given in Table 5.17. These results show that the effect of reinforcement varies from cement to cement but, in general, increases it. 

In conclusion, it may be mentioned that the characterization of the mechanical behaviour of materials has many facets. Different methods of testing pertain to different aspects and conditions. The tensile properties, as determined by the tensile test, correspond to slowly applied single load applications. Rapidly applied and cyclic load applications respectively provide the impact and the fatigue properties. Hardness is an analog of the tensile strength which a tensile test measures. The creep test pertains to mechanical behaviour under long term loading at elevated temperatures. 

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