204 research outputs found
MICROSTRUCTURAL CHARACTERIZATION AND FATIGUE BEHAVIOR OF COLD SPRAY COATED ALUMIUM ALLOY
No full textDifferent sets of Al5052 alloy specimens have been coated by pure Al and Al7075 alloy powder, using low pressure cold spray coating technique. The microstructural evolution of the substrate after coating and the fatigue behavior of the coated structure have been surveyed. In order to obtain the fatigue S-N diagram of each set, as received and coated specimens have been tested at load control condition.
The powders size distribution and shape has been studied by scanning electron microscopy (SEM). X- ray diffraction (XRD) has been used to measure the residual stress in both deposited material and the substrate. Grain size measurements are performed by XRD using a portable unit.
The results of different characterizing tests have been then discussed to highlight the effects of this emerging surface treatment on the characteristics of the treated material
Mesh sensitivity assessment of shot peening finite element simulation aimed at surface grain refinement
No full texthot peening process is widely used as a surface treatment for metallic components to generate surface compressive residual stresses, work harden the surface layer of material and consequently improve the component's fatigue behavior. Numerical simulation is much helpful to limit the costly and time consuming experiments. Thus several approaches have been suggested for numerical simulation of shot peening in the recent years. However no comprehensive assessment has been yet done to perform parametric study of the process and its favorable effects. This study has focused on numerical simulation of severe shot peening, generally aimed at creating a fine grained layer of material on surface of the treated part. Mesh size effects have been particularly studied and analyzed, not only on residual stress computation, which has been always dealt with, but also by considering the accumulated equivalent plastic strain (PEEQ). PEEQ is recognized as a key parameter in the development of grain refinement process. In the end, a practical method is suggested to estimate the value of PEEQ independent from element size to be employed for assessing the generation of refined grains
Numerical model of severe shot peening aimed to estimate surface nano crystallization of Al material
No full textOn the shot peening surface coverage and its assessment by means of finite element simulation: A critical review and some original developments
No full textSurface coverage is a major control parameter for shot peening and has substantial influence on the reliability and uniformity of the process. It restrains quality variations that may cause premature failure or malfunctioning of the treated part. Despite the role of surface coverage in process quality, a general description and a unique standard method for its practical control and prediction are not yet established. This paper provides a general review of the definitions and requirements of surface coverage, its practical, theoretical and computational evaluation approaches. In the end a statistical study is performed on a coverage estimation method already developed by the authors. The results of the statistical study result in development of a complementary technique for coverage assessment which ensures full coverage with an optimum number of impacts. Different models are explained and critically discussed
Experimental and numerical analysis of surface nanostructured materials obtained by high energy shot peening
No full textNumerical and experimental analysis of surface roughness generated by shot peening
No full textShot peening, apart from its various projected effects, modifies also the surface state of treated components in terms of surface irregularities. Bearing in mind that both the macroscopic and the microstructure surface characteristics strongly affect the mechanical structures’ functionality, it is essential to carefully study the surface state of treated components. To assess the surface roughness evolution induced by shot peening, a 3D finite element model of the process is used to investigate surface topography alterations
as a function of peening parameters and processing time.
Discrete data obtained from the numerical simulations are subsequently elaborated to calculate the conventional roughness parameters. The results obtained from the numerical simulations, correspond quite well with the roughness values measured experimentally on shot peened specimens.
It is indicated that the developed numerical model provides an efficient estimation of surface characteristics of shot peened specimens, in terms of surface roughness parameters and thus can be used to properly select the peening parameters considering the eventual surface roughness
- …
