a H	Hertzian contact width
A c,1	cross-sectional area
AR	particle aspect ratio
c	circumference of the wear track
C	compliance matrix
COF	coefficient of friction
ECD	equivalent particle circle diameter
E i	Young’s modulus
E IT	indentation modulus
F	normal load
h	lubricant gap
h 0	rigid body distance
h disk	height of the UHMWPE disk
h s,i	score height
H	normalized lubricant gap
H IT	indentation hardness
I D	D-band Raman intensity
I G	G-band Raman intensity
k	wear rate
l s,i	score length
m	cross rate constant
p	hydrodynamic pressure
p a	solid asperity pressure
p H	maximum Hertzian contact pressure
p t	total contact pressure
P	normalized hydrodynamic pressure
P a	normalized solid asperity pressure
P t	normalized total contact pressure
r c	curved wear calotte radius
R	pin radius
R	particle roundness
R i	worn pin radii
R q,i	root-mean-squared roughness
s	sliding distance
t c	coating thickness
t c,i	worn off coating thickness
u	sliding velocity
U	displacement vector
Uz	displacement in z-direction
W acc	accumulated wear volume
W p	micro-ploughed wear volume
W v	volumetric wear
x, y, z	cartesian space coordinates
α	cross time constant
$\dot{\gamma }$	shear rate
δi	elastic deformation
ε	strain tensor
η	viscosity
η0	zero shear viscosity
η∞	infinite shear viscosity
$\overline{\eta }$	normalized viscosity
θ	fractional film content
λ	fluid film parameter
ν	Poisson’s ratio
ρ	density
ρ0	base density
$\overline{\rho }$	normalized density
σ	stress tensor
Ω1	computation domain disk
Ω2	computation domain pin
Ωc	computation domain contact area