Investigation of the design of a metal-lined fully wrapped composite vessel under high internal pressure

WOS: 000285460200007In this study, a Type III composite pressure vessel (ISO 11439: 2000) loaded with high internal pressure is investigated in terms of the effect of the orientation of the element coordinate system while simulating the continuous variation of the fibre angle, the effect of symmetric and non-symmetric composite wall stacking sequences, and lastly, a stacking sequence evaluation for reducing the cylindrical section-end cap transition region stress concentration. The research was performed using an Ansys (R) model with 2.91 volume, 6061 T6 aluminium liner/Kevlar (R) 49-Epoxy vessel material, and a service internal pressure loading of 22 MPa. The results show that symmetric stacking sequences give higher burst pressures by up to 15%. Stacking sequence evaluations provided a further 7% pressure-carrying capacity as well as reduced stress concentration in the transition region. Finally, the Type III vessel under consideration provides a 45% lighter construction as compared with an all metal (Type I) vessel

An elasto-viscoplastic analysis of direct extrusion of a double base solid propellant

WOS: 000281499100005In this study, three-dimensional modelling of extrusion forming of a double base solid rocket propellant is performed on Ansys (R) finite element analysis program. Considering the contact effects and the time dependent viscous and plastic behaviour, the solid propellant is assumed to obey the large deformation elasto-viscoplastic material response during direct extrusion process. The deformed shape, hydrostatic pressure, contact stress, equivalent stress, total strain values are determined from the simulation in order to get insight into the mechanical extremity that the propellant has undergone during processing. Hydrostatic pressure and contact stress distributions have been found to be important parameters due to safety reasons of the nitro-glycerine content in the bulk of the propellant. (C) 2010 Elsevier Ltd. All rights reserved.State Planning Department (DPT)Turkiye Cumhuriyeti Kalkinma BakanligiThe authors wish to thank to the State Planning Department (DPT) for Financial support and to Turkish MKEK Barutsan Company for technical cooperation

The Effect of Crack Geometry on the Nondestructive Fault Detection in a Composite Beam

LUY, Murat/0000-0002-2378-0009; Orhan, Sadettin/0000-0002-9751-6665WOS: 000385376300006Defects in structures may be inherited from materials and manufacturing or they develop during service. Defects may cause catastrophic failure, which is why their detection and classification are important issues. Many aspects of defects have already been dealt with, but with wider applications of non-destructive testing methods to composite materials. However, the effect of arbitrary and random defect geometry on the applicability of these methods has been overlooked. In order to investigate this issue, this study carries out a free vibration analysis of a specially orthotropic cracked cantilever beam that was manufactured by Pultrusion. A new crack model, unlike the widely known V-shaped crack, is introduced and the effect of crack depth on the natural frequency is investigated, both experimentally and numerically. The results obtained from both the new- and the V-shaped models are compared with each other, and it is revealed that the results are not sensitive to the geometry change

Thermo-mechanical analysis of double base propellant combustion in a barrel

Accurate determination of burning characteristics of the propellant and thermo-mechanical loads acting on the barrel supports better gun design and its tactical use. As the frequency of successive shots changes, burning rate of the gun propellant also changes and consequently the bullet velocity and internal pressure of the barrel changes as well. In this work, combustion characteristics of double base propellants with various grain sizes and initial temperatures were determined by performing a series of shooting tests and employing a thermo-mechanical model with ABAQUS (R) finite element code. Effects of various grain sizes (300-425, 425-500, 500-600, 600-710, 710-850 mu m) and initial temperatures (-60, 20, 0, 20, and 60 degrees C) of double base propellants on internal pressure, bullet velocity and barrel heat transfer were investigated experimentally and computationally. Samples of propellants were tested in a shooting range by using a NATO standard small caliber barrel of 7.62 mm in diameter, and barrel internal pressure, bullet velocity and barrel surface temperatures were measured experimentally. The barrel experienced high thermal stresses during the shootings. Based on the comparisons between the simulations and the experiments, the finite element model was in agreement with the data within 90% accuracy. (C) 2016 Elsevier Ltd. All rights reserved