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Abstrak :
Front rail adalah komponen utama pada crumple zone kendaraan yang mampu menyerap sekitar 40% dari energi kinetik saat terjadi kecelakaan frontal. Komponen front rail ini umumnya terbuat dari baja struktur berdinding tipis. Pada saat kecelakaan komponen ini diharapkan dapat menyerap energi tumbukan melalui proses deformasi (progressive buckling) sehingga mengurangi kerusakan pada kompartemen penumpang dan memberikan efek perlambatan yang berada pada tingkat aman terhadap penumpang. Crush initiators digunakan untuk meningkatkan penyerapan energi dan mengurangi gaya tumbukan puncak pada saat awal kecelakaan. Penelitian ini bertujuan untuk mengetahui pengaruh Crush Initiators pada tabung persegi berdinding tipis produksi dalam negeri yang diaplikasikan pada prototipe front rail Mobil listrik Universitas Indonesia dalam meningkatkan penyerapan energi dan mengurangi gaya tumbukan puncak pada saat diberikan beban aksial baik secara kuasi statik maupun dinamis. Analisa dilakukan dengan membandingkan hasil eksperimen dengan hasil analisa numerik menggunakan metode elemen hingga nonlinier, ANSYS-LS-DYNA. Hasilnya menunjukkan pengaruh yang signifikan dari crush initiators terhadap penurunan gaya tumbukan awal dan peningkatan penyerapan energi serta menunjukkan pola yang hampir sama antara hasil eksperimen dengan hasil komputasi numerik. ...... Front rail columns are the main component on vehicle crumple zone that absorb approximately 40% of kinetic energy at the moment of a frontal crash. Generally the front rail columns are made from thin-walled structural steel. During a crash, a front rail column is expected to absorb crash kinetic energy trough plastic deformation energy (progressive buckling) thereby reducing damage on passanger compartment and giving the effect of deceleration on the safety level for passanger. Crush initiators are used to improve the energy absorption and reducing the peak crus load at the time of the initial accident. This research aimed to determine the effect of Crush Initiators on thin-walled square tube which is apllied to the prototype of front rail electric car University of Indonesia on increasing the energy absorption and reducing the peak crush load when given quasi static axial load and dynamic axial load. Analysis was conducted by comparing the experimental result with numerical study result which using finite element nonlinier method, ANSYS-LS-DYNA. The results show the significant effect from the crush initiators on decreasing the peak crush load and increasing the energy absorption and show a similar pattern between the experimental and the numerical study result.

Abstrak :
Penelitian ini membahas tentang pengecoran besi tuang nodular (BTN) dinding tipis sebagai alternatif bagi material aluminium pada aplikasinya di bidang otomotif dalam rangka penghematan energi. Permasalahan yang dihadapi adalah penurunan sifat mekanis akibat terbentuknya lapisan kulit pada BTN dinding tipis. Lapisan kulit terbentuk akibat terjadinya degradasi bentuk grafit nodul dalam logam cair di dinding cetakan pada saat pengecoran. Digunakan tiga jenis variabel dalam penelitian ini yang bertujuan untuk mengurangi ketebalan lapisan kulit : pelapis cetakan grafit yang bersifat aktif; MgO yang bersifat reaktif; dan metode pelapisan cetakan ganda MgO/grafit. Ketebalan rata-rata lapisan kulit paling tipis yang didapatkan dalam penelitian adalah sebesar 30,41µm dengan metode pelapisan cetakan ganda, lebih rendah 57% dari ketebalan lapisan kulit variabel pelapis cetakan MgO (71,46 µm) dan 60% dari ketebalan lapisan kulit variabel pelapis cetakan grafit (74,44 µm). Berkurangnya ketebalan lapisan kulit berpengaruh terhadap peningkatan sifat mekanis BTN sehingga didapatkan kekuatan tarik rata-rata sebesar 376 MPa dan elongasi rata-rata sebesar 2,76% pada variabel metode pelapisan cetakan ganda. Kekuatan tarik yang didapatkan dari variabel pelapisan cetakan ganda 69% lebih tinggi dari kekuatan tarik variabel pelapis cetakan MgO (223 MPa) dan 26% lebih tinggi dari variabel pelapis cetakan grafit (297 MPa). Elongasi variabel metode pelapisan cetakan ganda adalah yang paling tinggi sebesar 2,76%, atau 93% lebih tinggi dari elongasi variabel pelapis cetakan MgO (1,43%) dan grafit (1,43%).

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This research explains about thin wall ductile iron (TWDI) casting as an alternative for aluminum usage in automotive parts. The occurring problem in TWDI casting is the formation of casting skin which reduces mechanical properties of TWDI. Casting skin is formed by degradation of nodular graphite shape at the mould interface while casting process is in progress. Three variables were uside in this experiment : graphite as active mould coating, MgO as reactive mould coating, and MgO/graphite double layer coating method. Average casting skin thickness was found at lowest value in double layer coating method variable (30,41µm), 57% lower than casting skin thickness in MgO coating variable (71,46 µm) and 60% lower than graphite coating variable (74,44µm). The reduction of casting skin thickness increased the mechanical properties of TWDI so that highest UTS value of 346 MPa and elongation of 2,76% could be achieved by using double layer coating method, which UTS is 69% higher than using MgO coating variable (223 MPa) and 26% higher than using graphite coating variable (297 MPa). Elongation value achieved by using double layer coating method was the highest (2,7%), which was 93% higher than using MgO (1,43%) coating variable and graphite coating variable (1,43%).

Abstrak :
ABSTRAK Faktor keselamatan atau crashworthiness adalah hal terpenting dalam merancang suatu kendaraan. Struktur rel depan yang terletak di zona benturan berguna untuk dapat menyerap energi saat terjadi tabrakan dari arah depan, dengan begitu energi yang tersalurkan ke dalam kabin penumpang akan lebih kecil dan diharapkan tidak membahayakan penumpang. Struktur berdinding tipis banyak digunakan dalam aplikasi crashworthiness karena mempunyai rasio kekuatan dan berat struktur yang tinggi, harganya relatif murah, dan mempunyai kemampuan menyerap energi yang baik. Pada penelitian ini, pengaruh struktur baja persegi bernodal stiffeners dengan variasi desain ketebalan, bentuk, dan posisi dari nodal akan diamati sehingga mendapatkan nilai kriteria crashworthiness berupa penyerapan energi spesifik SEA , gaya tumbukan puncak peak force , dan efisiensi gaya tumbukan CFE . Pemberian nodal diharapkan dapat meningkatkan SEA dan CFE, lalu menurunkan nilai peak force. Setelah itu, urutan kombinasi desain optimum akan diperoleh dengan metode Vikor. Spesimen uji dengan faktor desain berbeda akan dilakukan uji simulasi numerik dengan memodelkan pengujian beban impak menggunakan software PAM-Crash. Variasi desain bentuk nodal penuh memiliki pengaruh paling besar terhadap nilai kriteria crashworthiness terbaik. Spesimen 12 0.8 F 150 sebagai kombinasi desain optimum.

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ABSTRACT Vehicle safety or crashworthiness is the most important factor to design a vehicle. The function of frontal rails which is located on crumple zone is to absorb energy when collision happens, so that the energy occur on passenger cell is minimized and less dangerous. Thin walled structures generally used in many applications of crashworthiness because it has high strength and weight ratio, inexpensive, and have a good energy absorber ability. In this study, the effect of nodal stiffeners with varied thickness, shape, and nodal position is observed to get a crashworthiness criterias, namely is specific energy absorption SEA , peak crushing force peak force , and crush force efficiency CFE . Nodal installations hopefully can increase SEA and CFE, then decrease peak force. After that, optimum design combinations obtained from Vikor method. Specimen with a different design factors will be done by modelling a numerical simulation based on real experimental case use PAM Crash software. The design variations that have a full nodal show a significant effect to crashworthiness criteria. Specimen 12 0.8 F 150 is the optimum design combinations.

Abstrak :
This book presents a collection of chapters on the current problems of the theory of dynamical processes in generalized continua and structures, and has been compiled to commemorate the 70th birthday of Prof. Dmitry Indeitsev-a leading specialist in the field of dynamical processes in solids, fluids and structures. It discusses various applications related to Prof. Indeitsevs contributions, including various discrete and continuous dynamic models of structures and media, as well as a number of dynamical processes in generalized media.

Abstrak :
This book presents a theoretical approach that allows the analysis of structures with magnetorheological and electrorheological layers, and shows, with the help of examples, how the mechanical behaviour of thin-walled laminated structures can be influenced. It consists of six chapters: Chapter 1 presents a brief overview of derivation approaches for theories of thin-walled structures, modelling of composites and modelling of laminated and sandwich structures. Chapter 2 describes the equivalent single layer model for thin laminated cylindrical shells, including the special cases of plates and beams. In addition to the classical mechanical properties, it also considers the electrorheological and magnetorheological properties. Chapter 3 presents the elastic buckling of laminated beams, plates, and cylindrical shells, discussing various problems, such as the influence of the boundary conditions, external loading and magnetic fields. It also suggests different approximations for asymptotic methods. Chapter 4 focuses on the free vibrations of elastic laminated beams, plates and cylindrical shells, investigating the influence of the boundary conditions and other factors. Chapter 5 presents the latest results concerning vibration of laminated structures composed of smart materials and discusses in detail the influence of electric and magnetic fields on smart structures. These results provide insights into the optimal design of these structures. Lastly, Chapter 6 features a short appendix presenting asymptotic estimates and series.