compression

In this study a new severe plastic deformation method named noncircular thin section cyclic extrusion–compression (NCTS-CEC) is proposed for processing ultrafine-grained noncircular thin section beams. In this technique, the total length of noncircular L shaped section is passed through a neck zone and experiences severe plastic strains. Therefore, the high amount of accumulated plastic strain could be imposed by repeating the number of process cycles. In the first section of study, the AM60 Magnesium alloy is inserted into die and deformed by punch in different cycles. The observations by optical and SEM microscopes showed the formation of about 5 μm fine grains from the initial value of 75 μm after processing by two cycles of the NCTS-CEC. Also, the mechanical properties including yield strength, UTS, elongation and microhardness are evaluated at different cycles of NCTS-CEC processing. The obtained results showed the increase of yield strength and UTS to 136.9MPa and 286.7 MPa from the initial values of 89.5 MPa and 227.3 MPa, respectively. The Vickers microhardness is increased to 89HV from the initial value of 54HV at the end of second cycle. Also, the elongation of processed sample is increased to 14.4% from 11.3% due to texture evolution, grain refinement and breakage of brittle eutectic phases at the end of second cycle. The cellular automaton (CA) finite element method was implemented to simulate the process to predict the microstructure evolution of AM60. The obtained results from cellular automaton finite element (CAFE) and experimental methods were in good agreement.

Increasing the range of conventional bullets has become very important today. Previous technologies increased the range of bullets by a certain amount. These former technologies in artillery shells include the technology of creating a bullet at the base of the bullet and the use of rocket bullet technology. Today, large research companies are using new technology to increase cannonballs. According to these companies, new technologies can increase the range of 155 mm bullets to 155 km. The new technology is the use of solid fuel ramjet technology, which is now very popular. Ramjet motors have no moving parts and at first glance look like a hollow tube, which is mostly used at supersonic speeds. In such engines, in order for the engine to start, the air speed must first reach the required value. In such a case, the ramjet engine will start automatically. In this research, the technology of ram jet bullets and the progress made in it have been investigated. According to the investigations, one of the most important future technologies in artillery shells is the use of ramjet technology.

In this study, the compression behavior of cardboard egg box cores with various stacking sequences used in sandwich structures is investigated both experimentally and numerically. A critical requirement of the design is that the structure is compatible with the environment (biodegradable), and its properties have been investigated through compression and tension testing. Egg boxes were chosen as the core material for sandwich structures due to their mechanical properties, excellent insulation properties, and strength. Also, the core shape in various stacking sequences were modeled in ABAQUS Finite Element code to simulate the behavior of the egg box core in compression. The results showed that the surrounding edges of the core were crushed and the truncated top region compressed. The increase in thickness of the egg boxes directly affected the compression properties. By doubling the thickness of the layers, the amount of energy absorbed by the core increased by more than 100%. By comparison of various stacking sequences of the cores, the one with double layers of the egg boxes overlapped showed an increase of 49% in stiffness, 108% in energy absorption, and 128% in strength. According to the results, the tangled arrangement of the second type of the core exhibits the highest load bearing, the greatest energy absorption, and less damage as compared to other core stacking sequences.

In piston engines, as the engine speed increases, the combustion cycle time decreases. Reducing the engine combustion cycle time, the opportunity for complete fuel combustion is reduced. As a result, in order to complete the fuel combustion, at high engine speeds, the spark plug must ignite sooner. Now that the natural gas flame is slower than gasoline, this problem is becoming more noticeable. As a result, the spark ignition timing should be increased further in CNG fuel mode than in the case of gasoline combustion. This leads to an increase in negative work during the compression phase, resulting in reduced cycle efficiency. Researchers have suggested adding hydrogen to improve natural gas combustion (HCNG). By adding hydrogen, the flammability properties of natural gas are improved. In this study, using Hydrogen generator, hydrogen and oxygen (HHO) gas is produced and consumed water by electrolysis method. The gas (HHO) produced together with the gas (CNG) is combined with the air entering the engine. Then the effect of gas (HHO-CNG) on the parameters of efficiency, power and pollution has been investigated. The results show that the thermal efficiency increases with the addition of HHO. Under these conditions, CO and UHC levels have decreased. This reduces contamination and increases efficiency due to reduced need for spark plug advance and complete fuel combustion.

The majority of corrugated boxes are transported and stored on pallets where the reduced support area due to deckboard gaps has an adverse effect on the strength of the corrugated boxes. Therefore, an adjustment factor is used to adjust the box compression strength to account for the lack of support, but these factors were developed for a limited range of deckboard gaps, box sizes, and box orientations. In addition. There is no predictive model that can estimate the reduction in compression strength based on the size of the box and the size of the gap. The main objective of this study was to investigate and predict the loss in compression strength produced by top deckboards with a wide range of gaps between them using empirical data from two different corrugated box sizes. Results indicated that corrugated box compression strength decreased as the gap between the pallet deckboards increased. Larger boxes(305 mm wide) were far less susceptible to the effect of gaps than the smaller boxes. A decrease in strength was observed when the location of the gap was relocated within 10 mm of the box corner. Gaps were found to produce the same reduction in compression strength when subdivided found the equation to be capable of predicting the loss in compression strength produced by gaps. The predictive accuracy was similar to the original McKee equation, and thus equally limited by the inherently large variation in corrugated boxes.