In this paper, we developed a virtual model predicting the tool deflection induced surface error and investigated the sensitivity and direction of the maximum surface error in various tool geometries and cutting conditions. The characteristics of the error were classified into the axial sensitive, radial sensitive, robust, overcut, and overlap zones according to the depth of cut. The maximum surface error was sensitive to the uncertainty of the radial depth of cut and robust to axial depth variation at the finishing process using a small radial depth of cut. The radial sensitivity was reduced by a large helix angle of tool. The sensitivity was decreased by increasing the depth of cut and it arrived at zero in the robust zone where the maximum surface error was not changed by both radial and axial depths of cut. An overcut occurred if axial and radial depths were deep and the overcut zone was enlarged by the helix angle and the number of teeth.

Incremental sheet metal forming can be used to manufacture various products without the punch and die set. However, it is difficult to manufacture the desired shape due to section deflection and springback of the sheet. Section deflection is caused by the force of the blank holder for fixing the sheet and the tool for forming the sheet. In this study, we analyzed the characteristics of the section deflection according to the geometries of the circular cup shapes in the sheet incremental forming process. The section deflection increased with an increase in the entering radius and forming angle in the section deflection region. However, section deflection was constant according to the exit radius. In addition, the secondary forming process for reducing the shape error was introduced. The secondary incremental forming process was conducted in the opposite direction. Characteristics of the shape error according to the entering depth of the tool among the forming parameters for reducing the shape error of the cup shape were analyzed. The springback in the cup-shape was reduced by the additional forming process with an optimum entering depth of the tool.

Since earth pressure changes depend on soil depth and surrounding situations, the construction of earth retaining temporary structures should be able to measure the change of the earth pressure and cope with the changes. When the underground excavation and construction of earth retaining temporary structure repeatedly occur, the excavation should be less interfered by the earth retaining structure. A PS synchronize wale measures the horizontal deflection of the structure and generates tension on the wire rope by controlling the hydraulic cylinder so that the wale is in safe range. Since the horizontal load is canceled by pre-stress bending moment, the number of struts the horizontal load is reduced making the excavation interference is small. We evaluated the horizontal deflection of the PS synchronize wale with increasing tension and verified that the deflection of the PS synchronize wale can cancel out the horizontal load in the safety range of 5 mm. This occurs through a universal testing machine experiment simulating earth pressure. We are in the process of applying the PS synchronize wale to a test bed and expect it to be safer and more efficient than existing methods.

The aim of this paper is the development of a PZT-driven apparatus for testing the force-deflection behavior of thin 0.1/0.5-㎜-thick plates. Thin plates are widely used as the diaphragm of pressure sensors, as they are much stronger than the thin films with thicknesses of up to several tens of ? that are used in MEMS applications. Therefore, a proper PZT actuator should be selected to acquire the static- and dynamic-material properties of these thin plates to perform testing in terms of the force and frequency responses. Based on the investigation of the PZT characteristics, a test apparatus is developed. It is verified for the Hastelloy C-276 that the static-force deflection, acquired through sample testing, is compatible with the theoretical one; moreover, the dynamic test is available up to approximately 20 ㎐.

In this study, a numerical analysis on the impact response of HHA (High Hardness Armor Plate) sequences under a 7.62 mm projectile impact was performed to obtain the fundamental design data for a combat-vehicle platform. Recently, the ballistic-protection levels for combat vehicles have increased, and ballistic-protection designs should now be able to deflect multi-hit projectiles. To study the ballistic-impact characteristics, armor-plate sequences of one or two layers with a gap of 0 mm to 2 mm between the front and rear plate were defined under the same weight and thickness. For the certification of the reliability of the numerical model, ballistic tests and an analysis of the single plate under the 7.62 mm projectile impact were performed and analyzed. On the basis of a valid numerical model, a numerical analysis was performed and analyzed. Lastly, it was proved that the performances of the two-layer sequence with the 2 mm gap regarding the impact-response acceleration, deflection efficiency, and penetration depth are the highest.