Oka Wear Model

The Oka or Impact Wear contact model extends any Base Model to give an estimation of erosion depth for Geometry surfaces due to particle impacts.

This model originates from the work by Oka and Yoshida (Oka and Yoshida, 2005). Erosive wear occurs when particles impact equipment surfaces. This type of wear can be modeled using the widely adopted Oka wear model (Oka and Yoshida, 2004), which predicts the volume of removed material due to particle impact as a function of the particle size, impact velocity, and impact angle. This model takes only two inputs - the Vickers hardness of the worn material and an empirical wear constant. The results are provided in terms of wear depth on Geometry mesh elements similar to the Archard Wear model.

The wear depth is determined as follows:

$D_{ω} = \frac{g (α) E (α) m_{p}}{A}$

Where d_w is the wear depth, α is the particle impact angle, g_(α) is the impact angle dependence of normalized erosion, E_(α) is the wear volume per unit mass, m_p is the mass of the particle and A is the Geometry element area.

The wear volume per unit mass is defined as:

$E_{(α)} = 65 W -^{k_{1}} {(\frac{υ}{104})}^{2.3 H_{υ}^{0.038}} {(\frac{D}{0.326})}^{0.19}$

Where W is the materials wear constant, v is the particles impact velocity, H_v is the Vickers hardness of worn material, D is the particle diameter and k₁ is an experimentally derived coefficient.

The impact angle dependence of normalized erosion is defined as:

$g (α) = \sin {(α)}^{0.71 H_{υ}^{0.14}} {(1 + H_{υ} (1 - \sin (α)))}^{2.4 H_{υ}^{- 0.94}}$

Where

$\sin {(α)}^{0.71 H_{υ}^{0.14}}$ captures the normalized erosion due to repeated deformation and

${(1 + H_{υ} (1 - \sin (α)))}^{2.4 H_{υ}^{- 0.94}}$ captures the cutting behavior of the impact. Using this model in EDEM requires the additional input of the material’s Vickers hardness, H_v(GPa), the material’s Wear Constant, W_Oka.


Interaction	Configurable Parameters	Position
Particle to Geometry	Assign a wear constant, the Vickers Hardness value for each Equipment Material-Particle interaction and Scaling Factor (if Deformation enabled).	Last

EDEM also provides the option to deform the Geometry according to the quantitative results given by the Impact Wear model.

In the Oka Wear Model Parameter values dialog box:

Select the Enable Deformationcheck box to enable Geometry deformation.
If you select Enable Deformation, you must specify the Scaling Factor which allows the deformation results to be scaled as desired.


Material	W_Oka	Vickers Hardness (GPa)
Carbon Steel	3	0.54 - 1.18
Stainless Steel	10	1.770
Aluminum	1000	0.36