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EN
In the paper cohesive model implemented in WARP3D code and an example simulation of crack growth analysis ispresented. Cohesive model is an effective tool for a crack growth analysis and it was a main reason to invent it. For the "dassica" constitutive equation the crack growth simulation in the finite element method (FEM) is not possible without an additional crack growth criterion. In the commercial FEM codes cohesive model is not very popular unfortunately. Usually it can be applied as user implemented elements. However there is a code free of charge with high reliability acknowledged in the literature with cohesive elements in standard library. This program is WARP3D and it is dedicated to numerical simulations of three dimensional fracture mechanics problems. The Dugdale's model, void creation, the cellular model of material, the cohesion-decohesion curve, behaviour of cohesive element, comparison of curve shapes for brittle and ductile fracture, the profile of the cohesive element in WARP3D, specimen geometry, changes of crack shape under increasing load, opening stress distribution in the uncracked ligament are presented in the paper.
2
EN
The 2d lattice model was used to analyse fracture processes in concrete at the meso-level. Concrete was described as a three-phase material (aggregate, interfacial transition zone and cement matrix). The calculations were carried out for concrete specimens subject mainly to uniaxial extension. The effect of the aggregate density investigated, In addition, a deterministic size effect was studied, The advantages and disadvantages of the model were outlined.
3
Content available remote Development of fracture processes in Silesian Carboniferous sandstones
EN
The development of fracture processes in selected Carboniferous rocks from the Upper Silesian Coal Basin is described, with particular regard to the behaviour of rock specimens in the post-failure stage. The fracture processes were monitored using the stress-strain relations, coupled with acoustic emission, recorded during loading. Energy accumulation and dissipation phenomena were observed during rock loading. Cracking was recorded on the stress-strain curves as deformation loops, accompanied by significant stress decreases, and as cyclic increases in acoustic emission activity. Observing and analysing stages of high acoustic emission and stress drops enabled determination of three ways ("schemes") in which fracture originated and developed during the post-critical stage. Scheme I is damage and movement of grains and rock cement, scheme II is destruction of single rock grains of particular resistance, and scheme III is a dislocational and slide deformation of the rock medium.
EN
This paper describes a trial of monitoring fracture processes of SiC fiber reinforced aluminum composites with embedded optical fiber. It was embedded in composites reinforced with SiC fiber of different volume fractions by the interphase forming/bonding method using copper insert. These composites were tensile tested with measuring optical transmission loss. The results show that breakage of optical fiber starts at smaller strain than that of SiC fiber. The embedded optical fiber works as an optical path even after severe multiple fractures. Optical transmission loss is dependent on the number of optical fiber breakages. As fracture of SiC fiber enhances that of optical fiber and is reflected on optical transmission loss, fractures of SiC fibers can be detected by monitoring of optical transmission loss. It can also reflect the type of fracture process of the composite, that is, cumulative or non-cumulative.
PL
W pracy opisano badania butli ES (epoksydowo-szklanych) ciśnieniem niszczącym. Posłużono się metodą tablicową do: projektowania, analizy nawijania i doboru nawoju dla butli ciśnieniowych. Przygotowano trzy rodzaje butli, o różnej strukturze przeplotów, które były obciążane ciśnieniem wewnętrznym do zniszczenia W czasie obciążania prowadzono pomiar emisji akustycznej (EA) oraz odkształcenia płaszcza nośnego w wybranych punktach. Wyniki badań pozwalają stwierdzić, iż liczba i rozmieszczenie przeplotów mają wpływ na sposób niszczenia płaszcza nośnego butli kompozytowej.
EN
In this paper a GRP vessel (epoxy resin and glass fibre) have been tested until destroying pressure. The table method has been used of: design, winding analysis and choice the wound for a pressure vessel. Three kinds of pressure vessels with a different structure of the interleave have been prepared. Vessels have been loaded by internal pressure. The acoustic emission and strain have been measured in a few selection point. Pressure test proved that the number and distribution of interleaves has a effect upon pressure vessel strength.
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