Abstract
The features of carrying out an autotechnical expertise (ATE) are considered in case the vehicles (V) participating in the road transport accident (RTA) don’t leave skid imprints. The examples of momentum and energy conservation law application are given at developing the road accident mathematical model. Special attention is paid to the determination methods of vehicle (V) velocity, travel directions in various RTA diagrams and archeology of deformation. For this purpose it is offered to draw a momentum vector diagram. It is reasonable that for the calculation of V deformation at RTA it is necessary to determine step by step the strain-stress state in a contact area on the basis of the theories of elasticity, plasticity, solid friction and finite-element methods. The technique of constructing an RTA mathematical model is developed. It is recommended to use at ATE of RTAs at the runs-over into the fixed obstacle (a stationary V) and collisions.
Highlights
From the formulae (15) and (16) we find the speed limit of one of the V before the collision above which they can move as a single whole, or, on the contrary, lower than which they remain on the road transport accident (RTA) scene
In case of the sliding blow at RTA, i.e. when changes of kinetic energy are connected with the incremental work of contact sliding friction forces, it is necessary to consider that in the formula (4) the coefficient of a contact sliding friction considerably differs from a sliding friction in kinematic couples
It is reasonable that for autotechnical expertise (ATE) carrying out at collisions and runs-over it is necessary to comprise the closed equations called mathematical model and including: formulae for braking path definition taking into account road conditions; energy and impulses conservation laws; analytical dependences for assessment of the stress-strain state on the basis of finite element methods, the plasticity deformation theory or the developed plastic deformation; impact mechanics and dynamics and others [20]
Summary
When carrying out an RTA ATE, investigating authorities most commonly put the following questions to the experts [1,2,3]:. As it is known [4,5,6], to answer the specified questions when carrying out ATE, the experts generally determine a stopping (S0) and a braking distance (ST) according to the following formulae: Sо =. Where j is a V deceleration during braking force acceleration to the largest extremum (ta); Su is a skid trace; Vps is V velocity at the moment of the first collision (run-over). Considering that the V with ABS at emergency brake application don't leave skid imprints virtually, the formulae (2) and (3) cannot be used to answer the raised questions. It is necessary to improve or develop new ATE methods, using laws of mechanics, the theory of ABS service properties, continuum mechanics and the theory of plasticity
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