To study the effect of the material and the roughness of the impact surface, the velocity of impact interaction and the properties of bodies on the value of the dynamic coefficient of friction, a shock testing machine is proposed that provides an impact contact effect on the bodies in a plane located at an angle adjustable from 0 to 45 ° relative to the normal line drawn to the point of impact, in the range of speeds from 12 to 72 m/sec. It is found that at an impact velocity of 25 m/sec with an increase in the angle of inclination of the impact steel plane, the angle of friction and the corresponding dynamic coefficient of friction increase in a linear relationship. The maximum values of angles φ and dynamic coefficients of friction f make: - for steel balls φ = 8.3°, f = 0.146; - for lead balls φ = 11.4°, f = 0.167; - for grains of the wheat φ = 6.8°, f = 0.12. The results obtained indicate that the elastoplastic properties and shape of the bodies do not have any significant effect on the angles of reflection of bodies from the impact plane.

The calculation of the coefficient of dynamism of the contact interaction of bodies (lead balls and wheat grains with a moisture content of 11.5%) was carried out based on the hypothesis of equality of the work consumed during static and dynamic deformation of bodies, according to the formula:Θ=(So+Su)/(Sod+Su),where So – residual deformation of the body under static loading;Sod – residual deformation of the body under dynamic loading;Su – elastic deformation under static and dynamic loading.The components of the formula were determined on specially designed devices:– on an electromechanical press with static interaction of bodies, at a deformation rate of 0,055 m/s, the following values were determined from the load – discharge diagrams: the value of elastic deformation Su and the maximum residual deformation of bodies So.– on a vertical copra (at a contact interaction speed of 1-2 m/s) and a shock stand (at an impact speed of 11-15 m/s), the residual Sod deformation was determined by the size of the contact spot on the bodies after the impact.The calculated values of the dynamism coefficient were:for lead balls – 1,4-2,1;for wheat grains – 1,3-1,45.The results obtained indicate that the value of the dynamism coefficient increases with increasing impact velocity, with the same work spent on deformation, since the proportion of residual deformation in the total deformation of bodies decreases (bodies are strengthened).It is advisable to continue experiments to determine the coefficient of dynamism of bodies depending on the impact velocity, the configuration of the impact surface and the physical properties of the contacting bodies.