Mechanical testing small punch

Recently, a modified small punch testing (MSP) method has been developed for mechanical evaluation of ceramic and ceramic/metal composite materials used in FGMs [5]. In the present study, the MSP method was applied to evaluate TiC-based ceramics, which are employed as ceramic-side materials in a TiC/Ni3Al FGM. Because the TiC/Ni3Al FGMs apparently show different damage behavior at temperatures from 1208 to 1373 K, the fracture strength and deformation of TiC-based ceramics were measured at these two critical temperatures. The differences in the behaviors of different TiC sintered bodies and their... 

Under biaxial drawing conditions of the small punch test (Edidin and Kurtz 2001), the large-deformation mechanical behavior of polyethylene also... 

This chapter reviews the development and application of miniature specimen mechanical testing techniques, based on the small punch test, to the characterization of UHMWPE components for total joint replacement. The development of the small punch test as applied to UHMWPE was motivated by two clinically relevant and related problems the relationship between process and system variables and polymer degradation, and the relationship between mechanical properties and the ensuing wear of the arthroplasty bearing. To a first order approximation, the polymer degradation problem was motivated by mechanical failure of tibial plateau bearings, and the wear problem was motivated by the clinical need to reduce the prevalence of small-particle mediated late-onset osteolysis in total hip arthroplasty systems. 

Kurtz S.M., J.R. Foulds, C.W. Jewett, et al. 1997. Validation of a small punch testing technique to characterize the mechanical behavior of ultra-high molecular weight polyethylene. Biomaterials 18 1659-1663. 

What are the advantages of the small punch test over standard mechanical test methods described in Chapter 12 ... 

Under biaxial drawing conditions of the small punch test [8], the large-deformation mechanical behavior of polyethylene also displays strong molecular weight dependence. Representative small punch test data, shown in Figure 2.3, were conducted at room temperature at a rate of 0.5 mm/min. 

How, then, are we to interpret values in the literature for in vivo oxidation in retrievals Current studies of mechanical behavior in shelf aged components and retrievals, whether based on miniature uniaxial tensile specimens or the small punch test, exhibit considerable variability and scatter, even when oxidation values are measured directly from the miniature specimens themselves. Consequently, published data for the relationship between in vivo oxidation and mechanical behavior are necessarily statistical in... 

Low oxidation (OI < 1) For ASTM oxidation index values of less than 1, it is very difficult to demonstrate a negative correlation with mechanical properties from retrievals, regardless of whether they are measured using miniature tension tests or small punch tests [16, 22, 34]. For this reason, oxidation indices of less than 1 may be considered relatively low, and despite evidence of early oxidative changes, it is unlikely that these changes have yet had a substantial negative impact on mechanical behavior. 

In summary, over the past decade the small punch test has been extensively developed to perniit direct assay of the mechanical properties of orthopedic UHMWPE bearings. 

Samples of punch-and-die pressing can be produced in a variety of home made or purchased small machines. The previously mentioned force/pressure test stands (Fig. 11.18), which may also use hydraulic actuation with hand or motor pumps, can be applied in connection with home made punch-and-die arrangements. Many laboratories are equipped with automatically or hand operated hydraulic laboratory presses, for example as shown in Fig. 11.20 (see also Fig. 8.92, Section 8.4.3). From the suppliers of such machines a large number of simple or sometimes highly sophisticated and automated presses are available. They are used for the determination of a variety of strength and force or pressure related product characteristics and, although the densification and compaction mechanisms are quite different from those of roller presses and can not be correlated, punch-and-die compacts are often made and evaluated to preliminarily investigate the compactibility of different feed materials or powder mixtures and to determine the type and amount of potential binders. 

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