scholarly journals Determination of the optimum ball radius for researching materials using ball indenting

2021 ◽  
Vol 5 (4) ◽  
pp. 227-232
Author(s):  
N. N. Avtonomov ◽  
A. V. Tololo
Keyword(s):  
Indentation Depth ◽  
Sample Material ◽  
Axial Deformation ◽  
Obvious Change ◽  
Actual Depth ◽  
Element Method ◽  
Load Indentation

The article discusses the study of the effect of a change in the radius of the ball in the injecting of the sample on the curve in the coordinates «load – indentation depth», the deviation of the indentation depth during elastoplastic indentation from the indentation depth with the elastic indentation and the amount of the axial deformation of the ball. The study was conducted using the Ansys Mechanical APDL program implementing the fenite element method. In the process of the study, it was found that with a change in the radius of the ball, there is no obvious change in the behavior of the sample material, and the deviation of the indentation depth during the elastoplastic indulgence from the indentation depth during the elastic indentation is not dependent on the size of the ball radius. There was also an effect of changing the radius of the ball on the size of the axial deformation of the ball and proposed a formula for determining the size of the axial deformation of the ball for the ball of any diameter, which will determine the actual depth of the ball into the ball when using the balls of different radius.

Determination of stress–strain curves of materials at high strain rates using dynamic indentation technique

2020 ◽  
pp. 030932472094864
Author(s):  
Samaneh Pourolajal ◽  
Gholam Hossein Majzoobi
Keyword(s):  
Indentation Depth ◽  
Indentation Test ◽  
Material Model ◽  
Optimization Techniques ◽  
Strain Rates ◽  
Stress Strain ◽  
Dynamic Indentation ◽  
Simulation And Optimization ◽  
Load Indentation

Determination of dynamic behaviour of materials is a serious challenge in mechanics of materials. In this investigation, a new approach is proposed to obtain stress–strain curves of metals from dynamic indentation test. This approach is based on a combined experiment, simulation, and optimization techniques. In the experiment side, a conical penetrator is shot against the material as the target. The load–indentation depth curve is obtained from the dynamic indentation test. The indentation test is simulated using Ls-dyna and the numerical load–indentation depth is obtained from the simulation. The stress–strain curves are defined by Johnson–Cook material model. From optimization of the difference between the experimental and numerical load–indentation depth curves, the constants of the material model are identified. The material model is validated also by stress–strain curves obtained from quasi-static test conducted using Instron and dynamic tests conducted using Split Hopkinson Bar. The results show a close agreement between the model prediction and the experimental stress–strain curves for different strain rates.

Effect of the Material Types on the Fundamental Frequencies of Uniaxial Composite Conical Springs

1999 ◽  
Author(s):  
Vebil Yildirim ◽  
Erol Sancaktar ◽  
Erhan Kiral
Keyword(s):  
Transfer Matrix Method ◽  
Pitch Angle ◽  
Natural Frequencies ◽  
Axial Deformation ◽  
Helical Springs ◽  
Fundamental Frequencies ◽  
Helix Pitch ◽  
Constant Pitch ◽  
Α Helix

Abstract This paper deals with the effect of the material types (Graphite-Epoxies and Kevlar-Epoxy) on the fundamental frequencies of uniaxial constant-pitch composite conical helical springs with solid circle section and fixed-fixed ends. The transfer matrix method is used for the determination of the fundamental natural frequencies. The rotary inertia, the shear and axial deformation effects are taken into account in the solution. The free vibrational charts for each material presented in this study cover the following vibrational parameters: n (number of active turns) = 5–10, α = (helix pitch angle) = 5° and 25°, R2/R1, (minimum to maximum radii of the cylinder) = 0.1 and 0.9, and Dmax/d (maximum cylinder to wire diameters) = 5 and 15. These charts can be used for the design of uniaxial composite conical springs.

scholarly journals Determination of mechanical properties by nanoindentation independently of indentation depth measurement

2012 ◽  
Vol 27 (19) ◽  
pp. 2551-2560 ◽  
Author(s):  
Gaylord Guillonneau ◽  
Guillaume Kermouche ◽  
Sandrine Bec ◽  
Jean-Luc Loubet
Keyword(s):  
Mechanical Properties ◽  
Indentation Depth ◽  
Depth Measurement ◽  
Image Position

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