Enoch, Jiya Adama (2015) Non-Destructive Crack Detection Technique by Means of Microwave Imaging. Masters thesis, Universiti Sains Malaysia.
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Abstract
Bangunan-bangunan dan struktur awam selalunya terbeban dengan beban melebihi had sehingga membawa kepada kemerosotan dan kelemahan struktur penahanan dan mengakibatkan keretakan. Keretakan dalam konkrit atau bahan berasaskan simen membawa ancaman besar kepada mana-mana struktur awam: ianya sangat berbahaya dan telah membawa kepada banyak kemusnahan dan kerosakan. Walaupun satu keretakan kecil yang kelihatan tidak penting boleh membesar sehingga akhirnya menyebabkan kegagalan struktur yang serius. Selain daripada pemeriksaan manual yang tidak efektif dan memakan masa, beberapa teknik ujian penilaian tanpa musnah pernah digunakan untuk mengesan keretakan. Contohnya, ultrasonik, getaran dan teknik regangan, namun ada di antara penderia yang digunakan samada terlalu besar ataupun beresolusi rendah. Objektif utama adalah untuk mengkaji kemungkinan pengesanan keretakan di dalam konkrit atau simen menggunakan gelombang mikro bersama dengan algoritma lengah-dan-campur. Pertama sekali model pelbagai jenis keretakan di dalam bata disimulasikan menggunakan teknik FDTD. Keputusan dari simulasi digunakan untuk menentukan parameter persediaan eksperimen. Bata dan struktur konkrit dengan keretakan telah digunakan sebagai bahan ujikaji. Daripada keputusan eksperimen, didapati isyarat dengan frekuensi 1 hingga 7 GHz menghasilkan resolusi dan penembusan yang optimum. Keretakan sekurang-kurangnya sebesar 5 mm telah berjaya dikesan dengan resolusi λ/4, yang membolehkan pengesanan keretakan tahap awal. Kesimpulannya teknik pengimejan gelombang mikro mempunyai potensi untuk mengesan keretakan di dalam konkrit atau bahan berasaskan simen dengan resolusi yang tinggi. ________________________________________________________________________________________________________________________ Building and civil structures are often overburdened with load above their threshold value that led to deterioration and weakening of the supporting members, and resulted in cracks. Cracks in concrete or cement based materials present a significant threat to any civil structures; they are very dangerous and have caused much destruction and damages. Even small cracks, which look insignificant grow and eventually lead to severe structural failure. Besides manual inspection that is ineffective and time-consuming, several non-destructive evaluation techniques have been used for crack detection. For instance, ultrasonic, vibration and strain-based techniques, however some of the sensors used are either too big or limited in resolution. The main objective is to study the possibility of crack detection in concrete or cement based materials using microwave imaging with Delay-and-Sum, (DAS) algorithm. First, models of various crack types in bricks were simulated using finite difference time domain method (FDTD) method. The simulation results were used to determine the design parameters for the experimental setup. Single brick and a constructed concrete structure with cracks were used as phantoms. From the experimental results, signal with frequency of 1 to 7 GHz gave an optimum resolution and signal penetration. Cracks of at least 5 mm in size were detected with a resolution of λ/4 that enabled crack detection at the early stage of development. In conclusion, microwave imaging technique showed the potential to detect cracks in concrete or cement-based materials with high-resolution image.
| Item Type: | Thesis (Masters) |
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| Additional Information: | full text available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=1959 |
| Subjects: | T Technology T Technology > TK Electrical Engineering. Electronics. Nuclear Engineering > TK1-9971 Electrical engineering. Electronics. Nuclear engineering |
| Divisions: | Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraaan Elektrik & Elektronik (School of Electrical & Electronic Engineering) > Thesis |
| Depositing User: | Mr Mohd Jasnizam Mohd Salleh |
| Date Deposited: | 06 Jun 2018 06:25 |
| Last Modified: | 06 Jun 2018 06:36 |
| URI: | http://eprints.usm.my/id/eprint/40701 |
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