This paper proposed the simulation model of the servo system with three-stage reducer and presented the result of frequency analysis of the servo system considering backlash ratios and motor input voltage. By virtue of this work, we realized that if the motor input voltage of the system was large, the influence of each stage backlash ratio could be minimized or removed. Besides, we also found that if the motor input voltage was small, this created an optimal backlash ratio combination which could maximize the anti-resonance and resonance frequency of the servo system. This paper could be useful for determining each stage backlash ratio in designing a three-stage geared servo system with fast response.

In this paper, the DSC and TGA for phenol and silica/phenolic composite were carried out by increasing temperature up to 950℃ with variable heating rate, to figure out basic thermal and pyrolysis characteristics of the composite. Also, the aim was to obtain the activation energy and the frequency factor which are the main parameters of the Arrhenius equation based on the Kissinger theory. The activation energy and frequency factor were used for the ablation model as material property. To confirm surface temperature distribution and recession of missiles, the CFD analysis using ANSYS Fluent R18.2 was performed to examine the thermal fluid characteristics of the hypersonic flight environment. Subsequently, the analysis results were applied as boundary conditions to a 2D axisymmetric pyrolysis and ablation model. Finally, pyrolysis and ablation analysis were performed using the ablation analysis code SAMCEF AMARYLLIS V.17, which uses the specific ablation module based on finite element code by applying carbon/phenolic and cork materials up to t = 10 s.

This paper addresses two methods to estimate the target incapacitation distance and probability of the arbitrary fragmentation warhead under the static detonation test condition. One is based on the probability equation suggested by Sperrazza and Kokinakis. The other is originated from the stationary detonation test concept to measure the performance of the fragmentation warhead. In the arbitrary fragmentation warhead, the target incapacitation probabilities obtained from the two methods were compared with each other. We found that the size of the fragment with cubic shape should be more than 3.5 mm to maximize the target incapacitation distance in the test method. And we also realized that the difference between the target incapacitation distance of the analysis method based on the test (AMBT) and that of the analysis method based on the probability equation (AMBPE) is decreased according to the increase of the fragment size. In conclusion, this paper can be useful for the estimation of the fragmentation warhead performance at the design stage.

This study proposed the proper detonation delay time of a main warhead after a precursor warhead detonation in an arbitrary tandem shaped charge missile as 407 μsec. In addition, the available detonation delay time range of the main warhead was proposed to be between 396 μsec and 418 μsec. The proposed figures were based on the analysis of the target protection capability and the scattering reactor behaviors of the explosive reactive armor with dual reactive panels. By virtue of this work, the determination of main warhead detonation delay time is more effective and convenient. Finally, the tandem shaped charge missile with more effective penetration performance also could be developed in the future.

A chemical ablation analysis of hypersonic missile for thermal protection design was performed using SAMCEF AMARYLLIS V.17, the specific ablation module of commercial software based on a finite element code. The pyrolysis and surface recession models based on the effects of mass loss, pore gas diffusion, and endothermic reaction energy were applied for non-linearity of material and boundary. The numerical studies were carried out to confirm the tendency of the pyrolysis and chemical ablation of theoretical ablative composite for open testing (TACOT) with a chemical composition similar to charring carbon/phenolic composites. The frequency of variation in surface recession, temperature, density and gas mass flux was reviewed to determine the characteristics of multiple decomposition reactions and oxidation via pyrolysis of gas species.