Mechanical

The problem of steady state cracking, in which the crack extends under a constant load, is investigated for two interface conditions: elastic (no slip) and frictional interface. The fibre, matrix and interface stresses in the cracked and uncracked regions of a unidirectional composite subjected to a remote axial stress are obtained using an improved shearlag theory that accounts for the axial and transverse load-carrying capacity of the matrix. The fibre axial stresses are the same as those of previous models. However, the matrix shear and transverse normal stresses predicted in the present model for the interface conditions are different, as are the critical cracking conditions considered. The critical cracking conditions are established using a generalized energy release rate formulation, and critical stresses are obtained in terms of microstructural properties of the constituents and the interface.

Reducing the emission pollution associated with oil combustion is gaining an increasing interest worldwide. Recently, Brown’s gas (HHO gas) has been introduced as an alternative clean source of energy. A system to generate HHO gas has been built and integrated with Honda G 200 (197 cc single cylinder engine). The results show that a mixture of HHO, air, and gasoline cause a reduction in the concentration of emission pollutant constituents and an enhancement in engine efficiency. The emission tests have been done with varying the engine speed. The results show that nitrogen monoxide (NO) and nitrogen oxides (NOX) have been reduced to about 50% when a mixture of HHO, air, and fuel was used. Moreover, the carbon monoxide concentration has been reduced to about 20%. Also a reduction in fuel consumption has been noticed and it ranges between 20% and 30%.

In this study, hydroxy gas (HHO) was produced by the electrolysis process of different electrolytes (KOH(aq), NaOH(aq), NaCl(aq)) with various electrode designs in a leak proof plexiglass reactor (hydrogen generator). Hydroxy gas was used as a supplementary fuel in a four cylinder, four stroke, compression ignition (CI) engine without any modification and without need for storage tanks. Its effects on exhaust emissions and engine performance characteristics were investigated. Experiments showed that constant HHO flow rate at low engine speeds (under the critical speed of 1750 rpm for this experimental study), turned advantages of HHO system into disadvantages for engine torque, carbon monoxide (CO), hydrocarbon (HC) emissions and specific fuel consumption (SFC). Investigations demonstrated that HHO flow rate had to be diminished in relation to engine speed below 1750 rpm due to the long opening time of intake manifolds at low speeds. This caused excessive volume occupation of hydroxy in cylinders which prevented correct air to be taken into the combustion chambers and consequently, decreased volumetric efficiency was inevitable. Decreased volumetric efficiency influenced combustion efficiency which had negative effects on engine torque and exhaust emissions. Therefore, a hydroxy electronic control unit (HECU) was designed and manufactured to decrease HHO flow rate by decreasing voltage and current automatically by programming the data logger to compensate disadvantages of HHO gas on SFC, engine torque and exhaust emissions under engine speed of 1750 rpm. The flow rate of HHO gas was measured by using various amounts of KOH, NaOH, NaCl (catalysts). These catalysts were added into the water to diminish hydrogen and oxygen bonds and NaOH was specified as the most appropriate catalyst. It was observed that if the molality of NaOH in solution exceeded 1% by mass, electrical current supplied from the battery increased dramatically due to the too much reduction of electrical resistance. HHO system addition to the engine without any modification resulted in increasing engine torque output by an average of 19.1%, reducing CO emissions by an average of 13.5%, HC emissions by an average of 5% and SFC by an average of 14%.

In a CANada Deuterium Uranium (CANDU) reactor, fuel channel integrity depends on the coolability of the moderator as an ultimate heat sink under transient conditions such as a loss of coolant accident (LOCA) with a coincidence of a loss of emergency core cooling (LOECC), as well as a normal operating condition. This study presents the assessments of moderator thermal–hydraulic characteristics in the normal operating condition and one transient condition for CANDU-6 reactors, using a general purpose three-dimensional computational fluid dynamics code. This study consists of two steps. First, an optimized calculation scheme is obtained by many-sided comparisons of the predicted results with the related experimental data, and by evaluating the fluid flow and temperature distributions. Then, in the second step, with the optimized scheme, the analyses for real CANDU-6 of normal operating condition and transition condition have been performed. The present model has successfully predicted the experimental results and also reasonably assessed the thermal–hydraulic characteristics of the real CANDU-6 with 380 fuel channels. Flow regime map with major parameters representing the flow pattern inside Calandria vessel has also proposed to be used as operational and/or regulatory guidelines.

This book is written as a text for advanced undergraduates and graduate students in aerospace, civil, and mechanical engineering and applied mechanics. It is also intended as a reference for practitioners. The book contains topics sufficient for two academic semesters or three quarters. Thus, there is enough variety that instructors of a one-semester course or one-or two-quarter courses can choose topics of interest to students.

This paper investigates the free vibration characteristics and stability of a functionally graded Timoshenko beam spinning with variable angular speed. Material properties of the beam are assumed to be varied continuously along the thickness of the beam according to a power law and exponential law. The results show that increasing beam rotational speed increases fundamental mode frequency and the beam becomes more and more stable at higher speeds. This paper reports the dynamic behaviour of a rotating FGM beam subjected to axial periodic forces using the finite element method. The numerical results show good agreement with the reported beams models. Effects of static and time dependent components of axial loads on the stability of the FGM beam have been studied.

Pulsed laser deposition is a technique that is capable of producing high quality multicomponent films under a broad range of ambient conditions. This technique has been widely used to grow thin films of numerous compounds. In particular, it enables the growth of films in reactive environments such as oxygen and nitrogen. Pulsed laser deposition of novel oxides such as cerium oxide (CeO 2), Gd doped cerium oxide (GDC) and La-Sr-Ga-Mg-O (LSGM) on (111) Si, (100) MgO, (100) YSZ and (012) sapphire substrates is demonstrated. A systematic study on the influence of the substrate temperature and substrate orientation on the growth characteristics of these oxides is reported.

Most studies on the application of natural fibers as reinforcement in polymer composites are growing as a result of the changes in characteristics that fibers can provide for the product. This can be achieved by manufacturing of composites using Hand Layup process. The 2% NaOH fiber treatment was performed to improve fiber-matrix interfaces making spathe- fibre-reinforced composites better mechanical characteristics. Filler loadings as 5% by volume of coir fiber are selected as reinforcement in composites. The varying lengths of fiber chosen as 5mm, 10mm & 15mm and resin-hardner ratio are maintained as 10:0.8. A total 3 numbers of plates with volume as 300 х 300 х 4 mm3 were produced and specimens as per the various ASTM standard were tested to determine the ultimate various Mechanical properties for different configuration. The strength of epoxy resin / coir fiber composites was noticed at a maximum 15 mm (15.27 N / mm2) fiber length. The maximum impact strength of the charpy was a...

The present work investigates the tensile and flexural strength of natural banana fiber composites. Natural fibers have incontrovertible advantages over synthetic reinforcing materials such as non-toxicity, low density, low cost, comparable durability, and limited waste disposal issues. Banana fiber reinforced composites are being prepared in the current experiment and the strength properties of these composites have been evaluated. Using the hand lay-up process, the composite specimens with variable fiber lengths were prepared and pressed at room temperature. Mechanical testing such as tensile, flexural are applied to the specimens. Analysis of the scanning electron microscope (SEM) is performed to examine fiber matrix interfaces and to analyze the fractured surface structure.

The aluminum metal matrix composites were broadly exploited in the applications of automotive, aerospace, and other defense with functionally graded materials-related application. Above applications definitely required excellent mechanical characteristics. Therefore, in this way, the major attempt was made on the nano-based composites with aluminum alloy utilization. In this research, aluminum alloy AA8011 and the ceramic-based reinforcement particles of nano boron carbide (B4C) were selected for producing the metal matrix composites by the liquefying process or stir casting route. The weight percentage of nano boron carbide particles having 15 wt% was subjected to add into the aluminum alloy during the stir casting process. Then, processed nano boron carbide and AA8011 specimens were prepared to conduct tribological behaviors with various processing conditions like sliding velocity, setting wear temperature, and applied load by the tribometer setup. The scanning electron microscope...

One recommended gait rehabilitation treatment after stroke is using ankle and foot orthotics. In clinical practice, it is essential to adjust the torque of the ankle-foot orthosis assistance to suit each patient's body function and gait ability. The present study investigated the effect of changing the plantar exion resistance of the ankle-foot orthosis on the post-stroke gait kinematics and kinetics during the early stance phase using a musculoskeletal model and an ankle-foot orthosis model. A prosthetic foot plate is designed, analyzed, and validates with the experiment work accomplished in this paper. A nite element (FE) model of the human foot was developed from 3D printing of 2 mm thick UK7 size. The nite element predictions are being validated theoretically and experimentally.