Papers by Keyword: Holes

Abstract: The glass fiber reinforced plastic (GFRP) composite materials are widely used in industries; these composites are coupled into large structures by drilled holes. In the present investigation, the characteristics of such drilled holes and defects were studied using GFRP composite samples with open-hole (at different positions), half-through holes and epoxy filled holes under three-point bend loading conditions. The “composite with epoxy filled holes” envisages maximum flexural strength, "composite with holes at a depth of 2.5 mm" showed intermediate and "composite with an open hole" exhibited minimum flexural strength. However, the flexural strength of the "composite" was increased when the relative distance between the holes was increased. The hypothesis of investigating the effect of defects in the form of Teflon exhibited significant results. The flexural strength was minimum in the case of multiple defects, however, it showed maximum fracture toughness. It was also observed that if the defect is present only at one end, it exhibited maximum flexural strength and minimum fracture toughness value.

Abstract: The research purpose is to develop an approach for determining the stress concentration near the holes in composite structure elements reinforced with carbon fibres. The research is performed on the basis of a numerical-analytic approach using the method of singular integral equations. The paper studies the stress concentration near the holes in composite plate elements of the structures, which are reinforced with carbon fibres. The stresses are determined based on the singular integral equations. The integral equations are solved numerically using the mechanical quadrature method. The stress in the strip is studied at: longitudinal tension; pure bending; three-point bending; with periodically spaced holes. An approach to calculating the stresses in composite strips weakened by holes of different shapes, based on the method of integral equations, has been developed. The equation kernels are formulated on the basis of Green's functions, under which the boundary conditions on straight-line boundaries are satisfied identically. A methodology for calculating the stress concentration near the holes of arbitrary shape in plate elements of the structures has been developed. The results obtained can be used when calculating the strength of composite materials reinforced with carbon fibres.

Abstract: An algorithm for determining the stress state of plates of different shapes with holes due to residual deformations was suggested. The residual stresses in the plates were determined using the calculation and experimental method. The algorithm for determining the stresses the near the holes in the plates due to residual deformations is based on the method of integral equations. The residual stresses and stresses near the holes were investigated. Stresses near circular holes with different distributions of plastic deformations were investigated. Cases were established, where at the boundary of holes, depending on their location, high compression or tensile stresses may arise. Particular, that high compression stresses appear at the point of intersection of the center of the weld with holes or outer boundary, which high compression stresses are approximately the same for all radii of the holes. In case of the radii of the holes that are smaller than the zone of plasticity, high tensile stresses appear, which decrease, when the size of the holes increases. In case of the radii of holes that are larger than the zone of plasticity, the maximum tensile stresses arise at points close to the boundary of the zone of plasticity.

Abstract: Positron annihilation lifetime spectroscopy (PALS) is a recognized instrument for the studies of size-distribution of nanopores (intrinsic free volume holes FVH) in polymers, particularly membrane materials. The limits of this application in the case of “alien” pores, produced by swelling of poly (hexafluoro propylene) PHFP in the gas (CO₂) in super-critical (sc-) state are discussed. The obtained conclusions are controlled by measurements of low temperature gas (N₂) sorption (LTGS) and by comparison of the data with the results on permeation of various gases through the PHFP membrane. Attention is payed to relaxation with time of the newly created FVH in the PHFP membrane.

Abstract: Abrasive Flow Machining method is an effective means for the common rail inside the tiny hole and cross-hole debarring polishing and machining. In this article, using FLUENT software analysis Abrasive Flow Machining common rail runner and three-dimensional numerical aperture structure, in the inlet velocity for the next 60m / s condition, contrast single, bilateral Abrasive Flow Machining method, derived both steady-state pressure, image analysis and comparison of the results of the dynamic pressure, velocity and turbulence kinetic energy, properly using numerical calculation to guide production process procedures, provide a reference for the optimization of the abrasive flow processing..

Abstract: Based on the eccentric compression performance testing of the out-of-planes of 4 pieces of different pre-stressed composite masonry walls with holes and constructional columns, the pre-stress’s influences on the horizontal and vertical transmission and distribution, emergence and development of cracks, deformation of the components and fracture morphology and mechanism of the section stress along composite wall with holes are revealed. The testing shows that the pre-stress not only improves comprehensively the load-carrying properties of composite wall, but its fracture mechanism and mechanical model are the same as that of the non-pre-stressed composite wall, so that the same design approach can be used. And it provides further experimental basis to supplement and improve the basic theory and computation methods of eccentric compression of composite wall’s out-of-plane in the current masonry structure specifications. Only crack resistance and bearing capacity are studied in this article.

Abstract: To study the carrying capacity of precast concrete pipe pile (PC pipe pile)with holes, the ABAQUS finite element software is used to simulate the experiment of the PC pipe pile with holes carrying capacity from different holes arrayments.The results showed that the strength of the PC pipe pile decreased after the area of holes increased.With the same area of holes,the increase in diameter of holes caused the strength decreased. Guidance would be given for the permeable PC pipe pile by the paper.

Abstract: Introduction of holes into plat-like structures is commonly found as one of practical noise control measures to reduce sound radiation. However, perforation into the panel also reduces the panel stiffness and hence increases its vibration. Since the discussion and also the analytical model to quantify this effect are lacking, this paper discusses the dynamics of a perforated panel from the results obtained using Finite Element Method (FEM). Different hole geometries are simulated to investigate their effect on the plate mobility. It is found that increasing the perforation ratio increases the plate mobility particularly at off-resonance peaks. The effect of hole size and number are also discussed in this report.

Abstract: The basic composition and working principle of the turret punch press were analyzed, the recent distance method and genetic algorithm optimize method of holes machining path of NC turret punch press was put forward, the corresponding mathematical model and optimization algorithm was respectively given, these two kinds of optimization methods aiming at different types of holes are compared with the examples, put forward a kind of the integrated holes machining path optimization.

Abstract: In this paper the study on lateral flexural-torsional buckling of steel sigma-cross-section beams with web holes will be presented. The analysis of corresponding stability problem is based on general approach derived for a group of beams including at least mono-symmetric sections loaded transversally to their plane of symmetry. The effective flexural and torsional stiffness of steel beams with holes has been verified by tests. The results of theoretical analysis were compared with specification design procedure and also with actual behaviour of set of beams investigated by experiments. The study conclusions aim to become the background of the supplements to specified provisions for the design of steel structures.