 a, $$\ \tau_\mathrm{a}$$ Adhesive shear strength kPa A Adhesive force on the blade kN BTS Brazilian Tensile Strength kPa c, $$\ \tau_\mathrm{c}$$ Cohesive shear strength kPa cm Mobilized cohesive shear strength kPa C Cohesive force on shear plane kN Esp Specific energy kPa F Force kN Fc Cutting force on chisel Evans model kN Fn Normal force on chisel Evans model kN Fch Horizontal force component Evans model kN Fcv Vertical force component Evans model kN Fh Horizontal cutting force kN Fv Vertical cutting force kN g Gravitational constant (9.81) m/s2 G Gravitational force kN hi Initial thickness of layer cut m hb Height of the blade m K1 Grain force on the shear plane kN K2 Grain force on the blade kN I Inertial force on the shear plane kN n Power in Nishimatsu model - N1 Normal grain force on shear plane kN N2 Normal grain force on blade kN p Stress in shear plane Nishimatsu model kPa p0 Stress at tip of chisel Nishimatsu model kPa Pc Cutting power kW Q Production m3 r Radius in Evans model m r Adhesion/cohesion ratio - r1 Pore pressure on shear plane/cohesion ratio - r2 Pore pressure on blade/cohesion ratio - R Radius of Mohr circle kPa R Force on chisel Evans model kN Rn Normal force on chisel surface Evans model kN Rf Friction force on chisel surface Evans model kN R1 Acting point on the shear plane m R2 Acting point on the blade m S1 Shear force due to internal friction on the shear plane kN S2 Shear force due to external friction on the blade kN T Tensile force kN UCS Unconfined Compressive Strength kPa vc Cutting velocity m/s w Width of the blade m W1 Force resulting from pore under pressure on the shear plane kN W2 Force resulting from pore under pressure on the blade kN α Blade angle rad β Angle of the shear plane with the direction of cutting velocityrad rad ε Angle of chisel with horizontal Evans model rad $$\ \tau$$ Shear stress kPa $$\ \tau_\mathrm{a}$$, a Adhesive shear strength (strain rate dependent) kPa $$\ \tau_\mathrm{c}$$, c Cohesive shear strength (strain rate dependent) kPa $$\ \tau_{\mathrm{S1}}$$ Average shear stress on the shear plane kPa $$\ \tau_{\mathrm{S2}}$$ Average shear stress on the blade kPa σ Normal stress kPa σC Center of Mohr circle kPa σT Tensile strength kPa σmin Minimum principal stress in Mohr circle kPa σN1 Average normal stress on the shear plane kPa σN2 Average normal stress on the blade kPa φ Angle of internal friction rad δ Angle of external friction rad λ Distance in Nishimatsu model m λs Strengthening factor - λ1 Acting point factor on the shear plane - λ2 Acting point factor on the blade - λHF Flow Type/Crushed Type horizontal force coefficient - λVF Flow Type/Crushed Type vertical force coefficient - λHT Tear Type/Chip Type horizontal force coefficient - λVT Tear Type/Chip Type vertical force coefficient - ω Angle in Evans model rad