Abstract:In this paper, authors present the study of free vibration of bending multiple cracked functionally graded material (FGM) beam. Vibration equations of multiple cracked FGM beam were established by using the rotational spring model of cracks, dynamic stiffness method (DSM) and actual position of neutral plane. The frequency equation obtained was in a simple form, that provides an effective approach to study not only free vibration of the beams but also inverse problems like identification of material and crack … Show more
“…Various problems in dynamic analysis of functionally graded beams were studied in the widespread literature, for instance, in the works [3][4][5][6][7]. A large number of works is devoted also to study vibrations of the beams with localized damages such as cracks [8][9][10][11][12][13]. Recently, some procedures were proposed by Yu and Chu [14]; Banerjee et al [15] and Khiem and Huyen [16] to detect cracks in functionally graded beams with natural frequencies measured by the traditional technique of modal testing.…”
The present paper addresses developing the Dynamic Stiffness Method (DSM) for natural frequency analysis of functionally graded beam with piezoelectric patch based on the Timoshenko beam theory and power law of material grading. Governing equations and general solution of free vibration are conducted for the beam element with piezoelectric layer that is modelled as a homogeneous Timoshenko beam. The obtained solution allows establishing dynamic stiffness matrix for modal analysis of FGM beam with bonded piezoelectric distributed sensors/actuators. Effect of thickness and position of the smart sensors/actuators and material parameters on natural frequencies is studied with the aim for dynamic testing and health monitoring of FGM structures. The theoretical developments are validated and illustrated by numerical examples.
“…Various problems in dynamic analysis of functionally graded beams were studied in the widespread literature, for instance, in the works [3][4][5][6][7]. A large number of works is devoted also to study vibrations of the beams with localized damages such as cracks [8][9][10][11][12][13]. Recently, some procedures were proposed by Yu and Chu [14]; Banerjee et al [15] and Khiem and Huyen [16] to detect cracks in functionally graded beams with natural frequencies measured by the traditional technique of modal testing.…”
The present paper addresses developing the Dynamic Stiffness Method (DSM) for natural frequency analysis of functionally graded beam with piezoelectric patch based on the Timoshenko beam theory and power law of material grading. Governing equations and general solution of free vibration are conducted for the beam element with piezoelectric layer that is modelled as a homogeneous Timoshenko beam. The obtained solution allows establishing dynamic stiffness matrix for modal analysis of FGM beam with bonded piezoelectric distributed sensors/actuators. Effect of thickness and position of the smart sensors/actuators and material parameters on natural frequencies is studied with the aim for dynamic testing and health monitoring of FGM structures. The theoretical developments are validated and illustrated by numerical examples.
“…Do đó, vấn đề xác định vết nứt trong kết cấu FGM là thực sự cần thiết và đã thu hút sự chú ý của nhiều nhà nghiên cứu trong và ngoài nước. Hầu hết các nghiên cứu hiện nay về xác định vị trí vết nứt trong kết cấu đều sử dụng phương pháp thí nghiệm không phá hủy dựa trên các đặc trưng động lực như là tần số, dạng dao động riêng, hàm phản ứng tần số,... Các đặc trưng động lực học của dầm FGM có vết nứt được xác định bằng các phương pháp giải tích [1][2][3][4][5][6], phương pháp bán giải tích Galerkin [7], phương pháp phần tử hữu hạn (FEM) [8][9][10], và phương pháp độ cứng động lực (DSM) [11][12][13][14].…”
Bài báo trình bày các kết quả nghiên cứu mới về việc xác định vết nứt trong các kết cấu hệ dầm bằng vật liệu có cơ tính biến thiên (FGM) dựa trên phân tích wavelet dừng (SWT) các dạng dao động riêng có kể đến ảnh hưởng của nhiễu trắng Gausian. Các dạng dao động riêng được xác định từ mô hình phần tử thanh FGM chịu kéo, nén và uốn có nhiều vết nứt theo mô hình lò xo bằng phương pháp độ cứng động lực (DSM). Kết quả nghiên cứu cho thấy phương pháp đề xuất là một phương pháp khả thi và hiệu quả.
Từ khóa: vết nứt; FGM; DSM; SWT; dạng dao động riêng.
“…The use of FG materials eliminates interlaminar stress concentration and due to its unique properties provides strength and toughness of the structure [2]. A large number of studies related to vibration characteristics of intact and cracked FG uniform beams are available [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Furthermore the studies have been extended in mechanical analysis of small-sized structures [23][24][25][26][27][28][29][30][31].…”
This paper presents the free vibration analysis of an edge cracked non-uniform symmetric beam made of functionally graded material. The Timoshenko beam theory is used for the finite element analysis of the multi-layered sandwich beam and the cantilever beam is modeled by 50 layers of material. The material properties vary continuously along the thickness direction according to the exponential and power laws. A MATLAB code is used to find the natural frequencies of two types of non-uniform beams, having a constant height but an exponential or linear width variation along the length of the beam. The natural frequencies of the beam are verified with ANSYS software as well as with available literature and good agreement is found. In the study, the effects of different parameters such as crack location, crack depth, power-law index, geometric index and taper ratio on natural frequencies are analyzed in detail.
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