FRACTOGRAPHY OF CAR ELECTRIC CIRCUIT COPPER CONDUCTOR FRACTURES

Data shown in the article give evidence that car fires refer to extremely serious accidents, therefore the problem of car fire safety enhancement is very topical. In this connection development of measures for car fire prevention is of great importance. One of preventive measures is fire investigation. In the article it is stated that them majority of conclusions of expert fire engineers regarding technical reasons for car fires has presumable (probable) nature which does not allow developing and implementing exact engineering solutions. This maybe explained by many reasons including absence of scientifically based methods. In particular, the problem of identifying primary, secondary short circuit or current overload in fusing copper conductor is not clearly solved, even though attempts to solve this problem using instrumental methods were made by criminalists starting from the 50^s of the last century. The article gives results of studying fracture surfaces of copper conductors exposed to high-temperature, secondary short circuit and current overload. To conduct study we used raster electronic microscope JSM-6390LV. It has been proved that on the fractures surface of copper conductors specific features for such as high temperature, secondary short circuit, current overload may occur in form of cell-type relief, microporosity, appearance ball-shaped microfusion around microcracks, steps on the fracture surface. Identification of such features allows identifying reason for destruction of copper conductor in case of fire and significantly simplifying determination of fire reason. It is found that the determined reasons are stable and not subject to changes in natural conditions of storing thermally damaged car. Data given in the article may be used by specialists in expert investigation of 12 V electric circuit copper conductors taken from fire locations, in identification of damage nature and, finally, in determination of car fire root cause.

короткое замыкание, токовая перегрузка, вторичное короткое замыкание, медь, растровая электронная микроскопия, медный проводник, фрактография, виды изломов, диагностический признак, пожарно-техническая экспертиза, short circuit, current overload, secondary short circuit, copper, raster electronic microscopy, copper conductor, fractography: fracture types, diagnostic feature, fire investigation

1. Брушлинский Н.Н., Соколов С. В., Вагнер П. Человечество и пожары. - М.: ООО "ИПЦ Маска", 2007. - 142 с.

2. Quintiere J. G. Fundamentals of fire phenomena. - England, Chichester : John Wiley and Sons Ltd, 2006. DOI: 10.1002/0470091150.fmatter.

3. Beyler C., Carpenter D., Dinenno P. Introduction to fire modeling. Fire Protection Handbook. - 20th ed. - Quincy : National Fire Protection Association, 2008.

4. Severy D., Blaisdell D., Kerkhoff J. Automotive Collision Fires // SAE Technical Paper 741180,1974. DOI: 10.4271/741180.

5. Katsuhiro Okamoto, Norimichi Watanabe, Yasuaki Hagimoto, Tadaomi Chigira, Ryoji Masano, Hitoshi Miura, Satoshi Ochiai, Hideki Satoh, Yohsuke Tamura, Kimio Hayano, Yasumasa Maeda, Jinji Suzuki. Burning behavior of sedan passenger cars // Fire Safety Journal. -2009. - Vol. 44, No. 3. - P. 301-310. DOI: 10.1016/j.firesaf.2008.07.001.

6. Богатищев А. И. Комплексные исследования пожароопасных режимов в сетях электрооборудования автотранспортных средств : дис.. канд. техн. наук. - М. : Академия ГПС МЧС России, 2002.-269 с.

7. Чешко И. Д. Экспертиза пожаров (объекты, методы, методики исследования) - 2-е изд., стереотип. - СПб. : СПб ИПБ МВД РФ, 1997. - 562 с.

8. Судебная экспертиза: типичные ошибки / Под. ред. Е. Р. Россинской. - М. : Проспект, 2014. - 544 с.

9. Delplace M., Vos E. Electric short circuits help the investigator determine where the fire started // Fire Technology. - 1983.-Vol. 19,No. 3. - Р. 185-191. DOI: 10.1007/bf02378698.

10. Babrauskas V. Arc beads from fires: Can 'cause' beads be distinguished from 'victim' beads by physical or chemical testing? // Journal of Fire Protection Engineering. - 2004. -Vol. 14, No. 2. - Р. 125-147. DOI: 10.1177/1042391504036450.

11. Wright S. A., Loud J. D., Blanchard R. A. Globules and beads: what do they indicate about small-diameter copper conductors that have been through a fire? // Fire Technology. -2015. -Vol. 51, No. 5. - Р. 1051-1070. DOI: 10.1007/s10694-014-0455-9.

12. Richard J. Roby, Jamie McAllister. Forensic Investigation Techniques for Inspecting Electrical Conductors Involved in Fire // Final Technical Report for AwardNo. 239052. - Columbia : Combustion Science & Engineering, Inc., 2012.

13. Фрактография и атлас фрактограмм: шрав. изд. /Пер. с англ.; под ред. Дж. Феллоуза. -М.: Металлургия, 1982. - 489 с.

14. Галишев М. А., Кондратьев С. А., Чешко И. Д., Шарапов С. В., Воронова В. Б. Руководство к практическим и лабораторным занятиям по расследованию и экспертизе пожаров : учебное пособие. - СПб. : Санкт-Петербургский институт ГПС МЧС России, 2003. - 110 с.

15. Мальцев М. В. Металлография промышленных цветных металлов и сплавов. - 2-е изд., перераб. и доп. - М. : Металлургия, 1970. - 364 с.

16. Недобитков А. И. Исследование жил медных проводников, находившихся в режиме перегрузки // Промышленность Казахстана. - 2015. - № 2. - C. 34-37.