Hasil Pencarian  ::  Simpan CSV :: Kembali

"Micromechanics of composites : multipole expansion approach is the first book to introduce micromechanics researchers to a more efficient and accurate alternative to computational micromechanics, which requires heavy computational effort and the need to extract meaningful data from a multitude of numbers produced by finite element software code. In this book Dr. Kushch demonstrates the development of the multipole expansion method, including recent new results in the theory of special functions and rigorous convergence proof of the obtained series solutions. The complete analytical solutions and accurate numerical data contained in the book have been obtained in a unified manner for a number of the multiple inclusion models of finite, semi, and infinite heterogeneous solids. Contemporary topics of micromechanics covered in the book include composites with imperfect and partially debonded interface, nanocomposites, cracked solids, statistics of the local fields, and brittle strength of disordered composites."

"This book, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed.The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. "

"Mathematics is a grand subject in the way it can be applied to various problems in science and engineering. To use mathematics, one needs to understand the physical context. The author uses mathematical techniques along with observations and experiments to give an in-depth look at models for mechanical vibrations, population dynamics, and traffic flow. Equal emphasis is placed on the mathematical formulation of the problem and the interpretation of the results. In the sections on mechanical vibrations and population dynamics, the author emphasizes the nonlinear aspects of ordinary differential equations and develops the concepts of equilibrium solutions and their stability. He introduces phase plane methods for the nonlinear pendulum and for predator-prey and competing species models. Haberman develops the method of characteristics to analyze the nonlinear partial differential equations that describe traffic flow. Fan-shaped characteristics describe the traffic situation that occurs when a traffic light turns green and shock waves describe the effects of a red light or traffic accident. Although it was written over 20 years ago, this book is still relevant. It is intended as an introduction to applied mathematics, but can be used for undergraduate courses in mathematical modeling or nonlinear dynamical systems or to supplement courses in ordinary or partial differential equations."

"This book gathers contributions addressing issues related to the analysis of composite structures, whose most relevant common thread is augmented numerical efficiency, which is more accurate for given computational costs than existing methods and methodologies. It first presents structural theories to deal with the anisotropy of composites and to embed multifield and nonlinear effects to extend design capabilities and provide methods of augmenting the fidelity of structural theories and lowering computational costs, including the finite element method. The second part of the book focuses on damage analysis; the multiscale and multicomponent nature of composites leads to extremely complex failure mechanisms, and predictive tools require physics-based models to reduce the need for fitting and tuning based on costly and lengthy experiments, and to lower computational costs; furthermore the correct monitoring of in-service damage is decisive in the context of damage tolerance. The third part then presents recent advances in embedding characterization and manufacturing effects in virtual testing. The book summarizes the outcomes of the FULLCOMP (FULLy integrated analysis, design, manufacturing, and health-monitoring of COMPosite structures) research project."

"Armor banyak dimanfaatkan pada bidang militer yang umumnya digunakan pada kendaraan militer seperti tank yang menggunakan baja. Namun, tank menggunakan baja terlalu berat sehingga dapat menghambat mobilitas kendaraan. Oleh Karena itu, diperlukan material yang lebih ringan, tetapi memiliki kekuatan mekanik dan ketahanan balistik yang sama atau lebih kuat dari baja. Paduan aluminium 7075 merupakan material yang memiliki kekuatan tinggi dan densitas yang lebih rendah dibandingkan dengan baja. Paduan ini dibuat menjadi material komposit dengan penguat nano silikon karbida (SiC). presentase volume penguat yang digunakan, yaitu 0%; 0.1%; 0.15%; 0.2%; 0.25%; dan 0.3%. Pada penelitian ini fabrikasi material komposit dengan metode stir casting dilanjutkan dengan metode squeeze casting dan juga dilakukan proses cold forging. Semua sampel komposit di uji balistik dengan Tipe III NIJ dan Tipe II NIJ. Karakterisasi lain seperti pengamatan metalografi, pengujian kekerasan, dan impak diambil baik dari data primer dan data sekunder. Hasil pengujian balistik, yaitu semua sampel tidak tahan balistik terhadap pengujian Tipe III NIJ, tetapi tahan balistik terhadap pengujian Tipe II NIJ kecuali sampel non forging dengan komposisi 0.1% SiC dan 0.15% SiC. Penambahan komposisi penguat nano dapat meningkatkan sifat mekanik kekerasan material, tetapi ketangguhannya menurun untuk sampel tidak dilakukan forging. Berdasarkan data sekunder sampel yang dilakukan forging dapat meningkatkan sifat mekanik material. Nilai kekerasan sampel non forging dengan komposisi 0.2% SiC dapat melampaui kekerasan baja karbon rendah untuk armor.

---

Armour is widely used in the military field which is generally used in military vehicles such as tanks that use steel. However, the tank uses steel and too heavy so that it can hamper the mobility of the vehicle. Therefore, we need a material that is lighter, but has the same or stronger mechanical strength and ballistic resistance than steel. Aluminum alloy 7075 is a material that has high strength and lower density than steel. This alloy is made into a metal matrix composite material with ceramic reinforcement such as nano silicon carbide (SiC) with a volume percentage of 0%; 0.1%; 0.15%; 0.2%; 0.25%; and 0.3%. In this study, the fabrication of composite materials using the stir casting method was followed by the squeeze casting method and the cold forging process was also carried out. All composite samples were ballistically tested with Type III NIJ and Type II NIJ. Other characterizations such as metallographic observations, hardness testing, and impact were taken from both primary and secondary data. The results of the ballistic test, that all samples were not ballistic resistant to the Type III NIJ test, but ballistic resistant to the Type II NIJ test except for non-forging samples with a composition of 0.1% SiC and 0.15% SiC. The addition of nano-reinforcing composition can increase the mechanical properties of the hardness of the material, but its toughness decreases for non forging samples. Based on secondary data, forging process on samples can improve the mechanical properties of the material. The hardness value of non forging samples with a composition of 0.2% SiC can exceed the hardness of low carbon steel for armour. "

"Indonesia merupakan negara tropis sehingga banyak tanaman yang tumbuh subur di dalamnya seperti tanaman serat. Serat alami merupakan serat yang ramah lingkungan, biodegradable, dapat didaur ulang, fleksibel, dan dapat meningkatkan sifat mekanik seperti serat kenaf Sumberejo. Tujuan penelitian ini adalah menganalisa nilai kekerasan, impak, dan ketahanan bakar pada komposit epoksi berpenguat serat kenaf Sumberejo dengan arah serat 0o/0o/0o/0o dan 0o/90o/0o/90o, yang difabrikasi dengan metode Vacuum Assisted Resin Infusion. Observasi mikroskop optik dilakukan pada permukaan sampel komposit epoksi berpenguat serat kenaf Sumberejo sebelum dan sesudah pengujian ketahanan bakar. Hasil yang didapatkan memiliki nilai kekerasan dan kuat impak yang sama pada arah serat 0o/0o/0o/0o dan 0o/90o/0o/90o, masing-masing adalah (71,48 ± 0,61) HD, dan (32,61 ± 1,28) J/cm2 untuk lamina 0o/0o/0o/0o, dan (72,4 ± 1,01) HD dan (33,03 ± 1,05) J/cm2 untuk lamina 0o/90o/0o/90o. Sementara ketahanan bakar tertinggi (14,0 ± 0,2) mm/menit pada KF/EP 0o/90o/0o/90o.

---

Indonesia is a tropical country which is many plants thrive. Natural fibers are environmentally friendly fibers, biodegradable, recycle, flexible, and might improve the mechanical properties such as Sumberejo Kenaf fiber. This research aims to analyze the hardness, impact, and fire resistance properties on kenaf fiber reinforced epoxy composites with fiber orientation, 0o/0o/0o/0o and 0o/90o/0o/90o, fabricated by the Vacuum Assisted Resin Infusion method. Optical microscope observation was carried out on the surface of Sumberejo kenaf fiber reinforced epoxy composites before and after the flammability test. The results of testing have the hardness and the impact strength with 0o/0o/0o/0o and 0o/90o/0o/90o fiber orientation, respectively (71,48 ± 0,61) HD and (32,61 ± 1,28) J/cm2 for laminate 0o/0o/0o/0o; (72,4 ± 1,01) HD and (33,03 ± 1,05) J/cm2 for laminate 0o/90o/0o/90o. Meanwhile, the higher fire resistance properties (14,0 ± 0,2) mm/minutes on KF/EP 0o/90o/0o/90o.

"