engleski

Evaluation of the Poisson's ratio from The 3D laser scanning data

Poisson's ratio represents the relation between lateral contraction/expansion and longitudinal extension/contraction of three dimensional bodies subjected to tensile/compressive loading. The Poisson's ratio can usually be evaluated from one dimensional tensile/compressive testing of cylindrical specimens.The measuring equipment usually consist of one dimensional mechanical calipers and micrometers, electronic extensometers or more advanced measuring techniques based on the photogrammetry. Such a direct contact measuring approach is not well situated for soft specimen where small contact force of measuring device significantly changes the specimen's dimensions and consequently influences the results. The specimen's cross section is often not cylindrical or loses the cylindrical shape during the deformation. In presented paper a more general approach based on a three-dimensional laser scanning technique and CAD model reconstructoin is reported. Three-dimensional laser scanning technique and 3D reconstruction based on the volumetric specimen changes enable more accurate evaluation of Poisson's ratio for soft materials. The CAD surface reconstruction enables the exclusion of zones near clamping jaws or compression plates that are influenced by the clamping forces (in tension) or friction (in compression).

Poisson's ratio; volume changes; 3D scanning

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