The study is focused on analysis of mechanical behavior of hen's eggshell expressed in terms of average rupture force and corresponding deformation. Some other physical properties such as mass, length, diameter, geometric mean diameter, surface area, sphericity, and volume were also evaluated. The egg samples were compressed along their X and Z-axes. Two different experimental methods were used: compression between two plates (loading rates 0.0167, 0.167, and 1.67 mm/s) and impact of a free-falling cylindrical bar (loading rates up to 17 mm/s). Surface displacement and surface velocity were measured using the laser-vibrometer. The increase in rupture force with loading rate was observed for loading in all direction (along main axes). Dependence of the rupture force on loading rate was quantified and described. The highest rupture force was obtained when the eggs were loaded along the X-axis. Compression along the Z-axis required the least compressive force to break the eggshells.

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The impulse stimulated thermal scattering experimental technique is used for contactless in situ detection of phase transitions in thin nickel-titanium films deposited on silicon substrates. It is shown that this technique enables thedetermination of thelocal properties of the film over a fully coated wafer, in particular the thickness of the film and the temperature dependence of theYoung's modulus, and canthus beused for monitoring of the spatial distribution of thefunctional properties in films prepared by a combinatorial sputtering approach.

NEDOMOVÁ ŠÁRKA, TRNKA JAN, STOKLASOVÁ PAVLA, BUCHAR JAROSLAV: Strength of coff ee beans under static and dynamic loading. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 3, pp. 743-749 Paper deals with experimental research on the crushing of coff ee beans of diff erent kinds under quasi-static and dynamic compression. The process of the crushing is described in details. It has been shown that there is variability in the crushing strength values. A relation between crushing strength and the coff ee grain shape is also studied. Roasted Arabica coff ee (Coff ea arabica) beans were used for analyses. Arabica coff ees were produced in diff erent countries. All Arabica samples were submitted to a light roast. The detail analysis of the experimental data shows that there is no signifi cant relation between parameters describing the fracture behaviour of the grains and grain geometry. These parameters are also independent on the grain weight. Compression of the coff ee grains leads to their crushing. The fracture force is diff erent for the diff erent kinds of the coff ee. The same is fact valid also for the strain at the fracture and for the energy absorbed during the grain crushing. Dynamic loading leads to the increase in the fracture force of coff ee grains in comparison with the quasi static loading. coff ee beans, compression loading, strength, impact loadingThe knowledge of the strength and toughness of the coff ee beans is necessary in order to evaluate their brittleness. The reaching of a certain degree of brittleness is very important for the grinding to which coff ee beans have to be subjected to before brewing. The uniformity of the product of the grinding process depends on various factors including the brittleness of the roasted coff ee bean and it aff ects the extraction of soluble solids to obtain the coff ee brew (Clo and Voilley, 1983;Clarke and Macrae, 1987). Even though the changes in the textural and mechanical characteristics to which the coff ee bean undergo during roasting play a relevant role in the quality of the roasted beans, these properties have been scarcely studied until now.The textural changes of coff ee beans during their roasting have been studied e.g. by Pitia et al. (2001) using of the static compression of the coff ee beans. The same technique has been used for the study of the infl uence of the moisture content and water activity on the mechanical properties of the coff ee beans (Pitia et al., 2007). This technique has been also used for the study of mechanical properties of many others beans, see e.g. (Tran et al., 1981, Borges andPeleg, 1997; Al Salah and Galland, 1985). In our previous paper (Nedomova, 2010) results on the coff ee grain compression has been presented. These results have been obtained for the quasi static loading.The grinding of the coff ee represents a loading process which is dynamic rather than static. It means the mechanical properties like crushing strength should be evaluated at the dynamic loading. In ...

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In advanced functional materials, where the prestress can initialize phase transitions or other structural changes, the effect of the increasing load on an acoustic wave velocity is substantial and can provide important information on the undergoing physical phenomena. In this paper, a novel method for contactless measurements of acousto-elastic parameters is presented. The contactless arrangement, based on the concept of laser-ultrasound, enables an accurate detection of small changes of the velocities of surface acoustic waves in various directions. Because of this contactless arrangement, the changes of the sample shape during the loading do not affect the results, which can be assumed as the main source of inaccuracy for classical contact methods. The experimental device and its control system is described in detail, and its application possibilities and limits are shown on examples of shape memory alloys.