ﺷﻨﺎﺳﺎﯾﯽ ﺗﺮك در ﺗﯿﺮﻫﺎ ﺗﺤﺖ اﺛﺮ ﻧﯿﺮوي ﻣﺘﺤﺮك ﺑﻪ ﮐﻤﮏ ﺗﺒﺪﯾﻞ ﻫﯿﻠﺒﺮت - ﻫﻮاﻧﮓ

Identification of Crack in Beams under Moving Forces Using Hilbert-Huang Transform

ﺷﻨﺎﺳﺎﯾﯽ و ﺗﺮﻣﯿﻢ ﺑﻪ ﻣﻮﻗﻊ آﺳﯿﺐ در ﺳﺎزه ﻫﺎ )ﻣﺎﻧﻨﺪ ﺗﺮك در ﻋﺮﺷﻪ ﭘﻞ ﻫﺎ( ، ﺑﻪ وﯾﮋه در ﺳﺎزه ﻫﺎﯾﯽ ﮐﻪ ﻫﻤﻮاره ﺗﺤﺖ ﺑﺎرﻫﺎي ﻣﺘﻨﺎوب ﻗﺮار دارﻧﺪ از اﻫﻤﯿﺖ ﺑﺴﺰاﯾﯽ ﺑﺮﺧﻮردار اﺳﺖ . در ﺳﺎﻟﯿﺎن اﺧﯿﺮ روش ﻫﺎي ﺟﺪﯾﺪي ﺑﺮ ﭘﺎﯾﻪ ﭘﺎﺳﺦ ﻫﺎي دﯾﻨﺎﻣﯿﮑﯽ ﺛﺒﺖ ﺷﺪه از ﺳﺎزه اراﺋﻪ ﺷﺪه اﺳﺖ ﮐﻪ اﮐﺜﺮ اﯾﻦ روش ﻫﺎ ﺑﺮ اﺳﺎس روش ﻫﺎي ﺑﻪ روز رﺳﺎﻧﯽ ﻣﺪل ﺗﻮﺳﻌﻪ ﯾﺎﻓﺘﻪ و ﻣﻌﻤﻮﻻً از ﻧﻈﺮ ﻣﺤﺎﺳﺒﺎﺗﯽ ﺑﺴﯿﺎر ﭘﺮ ﻫﺰﯾﻨﻪ ﻣﯽ ﺑﺎﺷﻨﺪ. ﺑﺮاي ﻏﻠﺒﻪ ﺑﺮ ﻣﺸﮑﻞ ﻓﻮق، در اﯾﻦ ﻣﻄﺎﻟﻌﻪ از ﯾﮏ روش ﺑﺮ ﭘﺎﯾﻪ ﺗﺒﺪﯾﻞ ﻫﯿﻠﺒﺮت-ﻫﻮاﻧﮓ اﺳﺘﻔﺎده ﻣﯽ ﺷﻮد. در اﯾﻦ روش ﭘﻞ ﺑﻪ ﺻﻮرت ﯾﮏ ﺗﯿﺮ اوﻟﺮ-ﺑﺮﻧﻮﻟﯽ و وﺳﯿ ﻧﻘﻠﯿﻪ ﻧﯿﺰ در ﭼﻬﺎر ﺣﺎﻟﺖ ﻣﺨﺘﻠﻒ ﺑﻪ ﺻﻮرت ﺑﺎر ﻣﺘﺤﺮك، ﺟﺮم ﻣﺘﺤﺮك، ﻧﻮﺳﺎﻧﮕﺮ ﻣﺘﺤﺮك و ﺳﯿﺴﺘﻢ ﻣﺘﺤﺮك ﻣﺪل ﻣﯽ ﺷﻮد. ﻧﺘﺎﯾﺞ ﻧﺸﺎن مي دﻫﻨﺪ ﮐﻪ در ﻫﻤﻪ ﺣﺎﻻت، روش ﺑﺮرﺳﯽ ﺷﺪه ﺑﺎ دﻗﺖ ﻗﺎﺑﻞ ﻗﺒﻮﻟﯽ ﻗﺎدر ﺑﻪ ﺷﻨﺎﺳﺎﯾﯽ ﺗﺮك در ﻋﺮﺷﻪ ﭘﻞ ﻫﺎ اﺳﺖ.

This article identifies crack in beams under moving forces (a moving load, a moving mass, a moving oscillator and a four degree of freedom moving system) using the Hilbert Huang transform. Timely identification and repair of damage in structures (such as cracks in bridge decks), especially in those structures that are always under dynamic loads, is very important. In recent years, new methods have been proposed based on the recorded dynamic responses of the structure. most of these methods are based on developed model updating methods which are usually very costly computationally. To overcome this problem, this study presents a method based on the Hilbert-Huang transform. In this method, the bridge is modeled in the form of an Euler-Bernoulli beam and the vehicle is also modeled in different conditions as a moving load, a moving mass, a moving oscillator and a moving system. The results show that the proposed method is able to detect cracks in bridge decks with an acceptable accuracy in all cases.