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Abstrak :
ABSTRAK
Pelat dan penegar merupakan bagian utama yang membetuk struktur kapal. Akan tetapi pelat dan penegar merupakan bagian dari kapal yang paling rentan mengalami retakan, hal ini dikarenakan struktur kapal merupakan bagian yang menopang beban yang diterima kapal. Cacat retak pada pelat kapal merupakan salah satu penyebab kegagalan suatu struktur kapal. Salah satu penyebab cacat retak adalah lingkungan yang korosif. Kapal yang pada umumnya terbuat dari baja dan berlayar dilaut, terutama di perairan asin, sangat rentan mengalami korosi. Korosi yang dialami pelat menimbulkan cacat retak pada permukaan pelat yang apabila dibiarkan maka cacat retak dapat menyebar. Hal ini disebabkan retakan mempengaruhi kemampuan struktur kapal menopang beban yang diberikan. Retakan akan menyebar lebih cepat akibat adanya gaya-gaya lateral dan momen lentur yang dipikul kapal. Penelitian ini berfokus untuk meninjau pengaruh dimensi retakan terhadap faktor konsentrasi tegangan SIF pada pelat kapal yang memiliki retakan korosi semi elliptical. Simulasi komputasi dengan metode finite element FEM dipilih sebagai metode untuk melakukan penelitian hasil ini. FEM dipilih dengan alasan agar perilaku pelat kapal yang mengalami retak dapat dipelajari dengan rinci, sejak saat pelat mulai mengalami retakan hingga mengalami perambatan retakan. Dengan menggunakan FEM di dapatkan hasil yang menunjukan bahwa dimensi retakan mempengaruhi faktor konsentrasi tegangan, dimana semakin besar dimensi retakan maka semakin besar faktor konsentrasi tegangannya.

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ABSTRACT<>br> Plates and stiffners are the main parts that make up the ship 39 s structure. Yet plates and stiffeners are one of the most vulnerable part of ships that easily cracked, this is because the ship rsquo s construction is the part that sustains the load received by the ship. Crack defects in plates are one of the causes for ship rsquo s structure failure. Corrosive environment is the cause for corrosion crack defects . Ships that are generally made of steel and sailed at sea, especially in salt waters, are particularly susceptible to corrosion. The corrosion experienced by the plate causing crack defects on the surface of the plate which, when left unchecked, cracks may spread and propagate. This is due to the crack affecting the ability of the ship structure to support the given load. Cracks will propagate faster due to lateral forces and bending moments on the ship. This study focuses on reviewing the effect of the crack dimensions on stress intensity factor SIF on ship plates with rusted semi elliptical cracks. Computational simulation with finite element method FEM was chosen as a method to conduct research . FEM was chosen because the crack plate behavior can be studied in detail, from the time the plate starts cracking to crack propagation. The results by using FEM indicating that the crack dimension influences the stress intensity factor, where the greater the dimension of the crack the greater the stress intensity factor.

Abstrak :
This study explores the effect of increased concrete strength on the behavior of concrete failure. Experimental testing using a three-point bend (TPB) test proposed by RILEM was carried out to calculate the value of fracture energy (GF), stress intensity factor (KIC), and characteristic length (lch) of the concrete. The values of GF and lch, which are proportional to the fracture process zone based on the fictitious crack model, were employed to determine the effect of concrete strength on the concrete’s fracture characteristic. KIC was engaged to describe the initial crack in the concrete. Four different concrete strengths of 40, 47, 53, and 100 MPa—were manufactured to produce notched beam specimens with single-sized notches 25 mm deep. Results revealed that the values of GF and KIC increased in the stronger concretes. However, the value of lch decreased significantly as concrete strength increased.

Abstrak :
Aluminum alloys, such as A6061-T6, are widely used in engineering components. However, detailed knowledge is needed to understand the way they respond to a fracture due to mechanical loading. Fractures occur in the structural component from crack propagation, and it is important to understand the mixed mode fracture behavior of crack growth. In this research, mixed mode fracture testing was conducted on the aluminum alloy A6061-T6 by employing a compact tension shear specimen. Crack growth behavior was investigated by applying a quasi-static loading at a constant cross-head speed using a Servopulser universal testing machine. The crack growths were observed by a Keyence digital microscope, and the critical stress intensity factors of the material were examined. Results showed that the shear type of crack initiation preceded the opening-type fracture. The dimple-type fracture on the fracture surface occurred under mode I and mixed mode with a loading angle of about 60o and 75o, respectively. The transition of crack initiation behavior from the opening-type fracture to the shear-type fracture occurred at a loading angle from 15o to 30o. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode at a loading angle 60o and 75o, respectively, for the compact tension shear specimen. Crack propagation behavior with three small holes occurring in a zigzag pattern ahead of the crack tip showed that crack initiation and propagation occurred only in the opening-type fracture. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode with a lower mode II component at a loading angle of 75o. When the small holes occured inline, there were two types of fractures occurring: an opening fracture at crack initiation and then crack propagation caused by shear fracture.