Since China's open forensic examination of traffic accidents, traffic police and judicial identification with many parties involved in the accident to consult some accidents, especially the speed calculation.

   The currently used most is the deformation calculation of automobile collision energy loss, namely the velocity change value. On the basis of the calculation of deformation and deformation stiffness.

   The following issues for deformation:

   1. deformation of the actual size and position measurement of improper or measurement error.

    1) such as car rear truck or side edge collision, longitudinal deformation is large, but the stiffness is. That is to say, the car frame with large stiffness (Zong Hengliang) almost no deformation.

   2) some accident calculation of the deformation is 1.4m or 1.6m, the actualEffective deformationBut 0.2m-0.4m.

   3) sometimes seem large deformation, the real effective deformation is small, such as tear and edge.

   4) truck, bus, car, car rear lateral deformationThere is no effective empirical formula(results).

  2 collision deformation stiffness

   1) is currently used on Japan in first Century, according to experts given positiveSide impact testThe stiffness coefficient. After nearly 40 years, great changes have taken place in the structure of car body stiffness, also has the very big change. These conclusions have been failure on the basis of test.

   In fact, in addition to 2) of domestic cars, mainly Europe and the United States and Japan Automobile Manufacturers in the collision car stiffness values can be found (get), there is no need to use outdated.

  3) even if the calculation formula of industry standard, also have certain application conditions. For example, manual calculation is generally some frontal collision resulting stiffness, but the testing speed is 50km/h.If the accident effectively speed is greater than 50km/h, the calculation speed stiffness formula is not valid. That is to say, the existing calculation formula is only suitable for the effective collision velocity is less than 50km/h. If the two car the same quality, same speed frontal collision, when the speed is greater than 25km/h, calculation formula is invalid. This is mathematically correct errors, in fact, is the extension of engineering.

   So someone says, the computing speed is very difficult, in fact is not difficult. According to the deformation characteristics of accident and general speed, using appropriate methods can accurately determine the speed of change in the process of accident collision rate.