Použití metody konečných prvků pro předpověď mechanických vlastností žárově nanášených vrstev

Feasibility of finite elemenent method (FEM) for prediction of mechanical properties of thermally sprayed coatings was studied. First, finite element models of microstructures with idealized pores were designed. The influence of pores presence on mechanical response of the structure was evaluated. Secondly, mathematical model based on real tungsten coating microstructure was created using OOF2 software and submitted for further FEM analysis using ABAQUS CAE. Values of Young’s moduli in in-plane and out-of plane directions were estimated. The predictions are compared to the experimental data

Tungsten-steel composites and FGMs prepared by argon-shrouded plasma spraying

International audienc

Hot tube forming

Tube forming is used to manufacture hollow geometries, otherwise would be stamped and welded. Automotive components could be produced by simply bending and preforming of tubular blanks; or by tube hydroforming (THF). Until recently, THF was limited to aluminum alloys and steels up to 1000 MPa tensile strength. Nowadays, hot tube hydroforming and tube bending & quenching processes are used in automotive industry to produce complex parts over 1500 MPa tensile strength

Residual strain and fracture response of Al2O3 coatings deposited via APS and HVOF techniques

The aim of this investigation was to nondestructively evaluate the residual stress profile in two commercially available alumina/substrate coating systems and relate residual stress changes with the fracture response. Neutron diffraction, due to its high penetration depth, was used to measure residual strain in conventional air plasma-sprayed (APS) and finer powder high velocity oxy-fuel (HVOF (θ-gun))-sprayed Al 2 O 3 coating/substrate systems. The purpose of this comparison was to ascertain if finer powder Al 2 O 3 coatings deposited via θ-gun can provide improved residual stress and fracture response in comparison to conventional APS coatings. To obtain a through thickness residual strain profile with high resolution, a partially submerged beam was used for measurements near the coating surface, and a beam submerged in the coating and substrate materials near the coating-substrate interface. By using the fast vertical scanning method, with careful leveling of the specimen using theodolites, the coating surface and the coating/substrate interface were located with an accuracy of about 50 μm. The results show that the through thickness residual strain in the APS coating was mainly tensile, whereas the HVOF coating had both compressive and tensile residual strains. Further analysis interlinking Vickers indentation fracture behavior using acoustic emission (AE) was conducted. The microstructural differences along with the nature and magnitude of the residual strain fields had a direct effect on the fracture response of the two coatings during the indentation process. © 2012, Springer. The original publication is available at www.springerlink.co