In this study, the crashworthiness of a medium heavy vehicle onto a designed security road blocker (SRB) as a vehicle barrier is studied numerically and compared with full-scale on-site crash test results in the literature. Structural integrity of the road blocker is studied by nonlinear dynamic methods under the loading conditions which are defined in the standards (ASTM F2656-07). Ls-Dyna ® software is used to solve the problem numerically. The penetration of the leading edge of the vehicle with respect to the attack face of the blocker is given both experimentally and numerically. Test and numerical results are compared. The comparison shows that; numerical results are in good agreement with the test results.

Experimental structural response of equipment mounted in store carried externally by jet type aircraft is investigated, predicted and compared with responses suggested by military standards in this study. A representative store which is similar to Mark-83 warhead with guidance units in terms of mass and geometry is used in this study. The main scope of this study is to evaluate the structural response proposed by military standards with real test conditions and also suggest a new method with an artificial neural network to predict the maximum response. Seventy-five different flight conditions are used to train the network for low and high frequency components. Also, eight flight conditions apart from the training set of flight conditions are used to test the approach. Acceleration levels are collected in real flight conditions by the data storage system. In signal processing, vibration response is expressed as power spectral density functions in the frequency domain. Procedures to predict the maximum response from measurements are determined with statistical limits in the literature. Besides the well-known limits in literature, third-order polynomial normal and logarithmic transform is used, and the performance of the different limits is compared. It is found that the military standard vibration spectrum is conservative. Distribution-free and normal tolerance limits predicted low frequency acceleration spectral density magnitudes more accurately. Their prediction performances were better than those of the other tolerance limits and that of the military standard. Third-order polynomial transform predictions are found to be reasonable with respect to normal prediction limit and envelope approach. Finally, it can be concluded that the response prediction method proposed in this article works well for Mark-83 warheads with guidance unit carried externally by jet fighter.

In this study, stiffness equivalent finite element modelling (EFEM) technique of a physical assembly which has several detailed electronic, mechanic and hydraulic parts is presented. Physical assembly can be evaluated as a subsystem. Outer geometry of the detailed subsystem is meshed by shell elements. Beam elements, of which cross sectional dimensions are found by structural optimization, are used at the inner section of the subsystem. To reach structural integrity, beam elements are connected to the outer shell with rigid elements. The deflection results of the detailed finite element model (DFEM) which is constructed by 3D solid elements are investigated under unit force laterally. The deflection results are defined as objective function in structural optimization of the EFEM. Design parameters are selected as rectangular cross section dimensions of the beam elements. The deflection results of the EFEM with optimized beam cross sections and DFEM indicate good agreement. Moreover EFEM is computationally efficient for the deflection analysis. It is shown that EFEM solution time is %1 of the DFEM.

 Aerospace structure design of payload equipment using structural response  Comparison of military specification and test results effects on structural parts used in aerospace application  Structural optimization based on vibration response Structural optimization of equipment assembled to payload of aircraft are performed by using the loads: artificial neural network (ANN) prediction, experimental and military specification (MIL-STD-810).The main scope of this study is to calculate the structural response limits that defined in military specification with real environmental conditions and also demonstrate the influence of usage ANN predicted and military specification loads in design purposes. Loads used in this study is taken from physically representative Mark-83 with guidance units. Predefined structural responses in optimization is used as power spectral density (PSD) functions in the frequency domain. Loads for structural design purpose are calculated with random loads using PSD data. Three sigma rule is considered between 20-300 Hz frequency bandwidth. A support structure is optimized according to the ANN predictions, military specification suggestions and experimental design loads. Figure A. Random vibration loads converted to static loads for design purposesPurpose: The aim of this study is to evaluate the structural responses proposed by military specifications with real test conditions and also compare the effects of usage ANN predicted and military specification loads in design of aerospace structures. Theory and Methods:Vibration responses in structural design is used as PSD in the frequency domain. Loads for structural design purposes are calculated with random loads using PSD data between 20-300 Hz frequency bands. Results:An aerospace structure is designed according to the ANN predictions, military specification proposal and experimental design loads. Supports designed based on experimental and predicted loads are lighter than the support designed according to the military specification load. Conclusion:It was observed that military specification loads exhibit conservatism. This conservatism makes the aerospace structures complex and heavier. Also, more engineering effort and production cost is occurred since the loads are high with respect to real environmental conditions.