Experimental evaluation and simulation on aging characteristics of aluminised AP-HTPB composite solid propellant

Abstract

The aging behaviour of ammonium perchlorate hydroxyl terminated polybutadiene composite solid propellant was characterised using uni-axial tensile and stress relaxation mechanical property measurements at regular intervals during an accelerated aging period. The measured properties in the tension test were Young's modulus, breaking load and percentage of elongation at the time of break. In stress relaxation test, the load at the end of 180 min of relaxation was recorded and it was selected as one of the indicators for the study of aging behaviour. Scanning electron microscopy examinations were also conducted for the fractured tensile test specimens during the aging period to observe the microscopic structure of the fractured surface of the propellant after tension test. Relaxation tests with 5% constant strain with 3 h hold duration were simulated using a finite element computer program. The reaction forces were collected for the period of hold duration and compared with the experimental results. The simulated results are in good agreement with experimental results. List of symbolsAP ammonium perchlorate de/dt, dD/dt strain rate E 0 Young's modulus G shear modulus G a final shear modulus G i initial shear modulus HTPB hydroxyl terminated poly butadiene K bulk modulus K a final bulk modulus K i initial bulk modulus k[t] rate of change of property RH relative humidity P(t) property at any time under accelerated aging P o initial property t time t o initial time UTM universal testing machine a i , t i Prony coefficients e strain s stress t relaxation time constant n Poisson's ratio

Study on master curve of tensile strength of thermal aging composite modified double base propellant

“…It can be seen from Fig. 2(a)-(d) that the relationship between the maximum tensile strength m of CMDB propellant and aging time is nonlinear under different test conditions, which is different from the relationship between the maximum tensile strength and aging time of HTPB propellant at room temperature and quasi-static tensile conditions [1] . Meanwhile, when tested at 253 K temperature, the maximum tensile strength increases first and then decreases with the increase of aging time, as shown in Fig.…”

“…Solid propellant is the power source of solid rocket motor and its mechanical properties and stability are related to the structural integrity of solid rocket motor. In order to accurately analyze the structural integrity of solid rocket engine, it is necessary to study the mechanical behavior of solid propellant under different conditions [1] . In the long-term storage process, due to the presence of chemical reactions and physical damage, the mechanical properties of solid propellant will continuously decrease with the increase of storage time, thus affecting the service life of solid rocket engine [2] .…”

Experimental Investigation and Modeling the Compressive Behavior of NEPE Propellant under Confining Pressure

“…In recent years, numerous researchers have conducted a wide range of tests to characterize the mechanical properties of solid propellants. These studies mainly focus on the low temperature, low/middle/high strain rates, aging, and tension/compression [6–10]. However, these studies were carried out under room pressure (atmospheric pressure).…”

Closed vessel burning behavior and ballistic properties of artificially-degraded spherical double-base propellants stabilized with diphenylamine

“…The decomposition reactions described above cannot be prevented, but the addition of an organic compound containing secondary amines, such as diphenylamine (DPA), 2-nitrophenylamine (2-NDPA) or urea derivatives (e.g. ethyl or methyl centralyte), absorbs the NOx gases released during the decomposition of the nitrate esters, thus delaying autocatalytic degradation and preserving the base components in the original composition [7,11,12]. DPA and 2-NDPA are often added to nitrate ester-based gun propellants at concentrations ranging from 1 to 3% (w/w) [13].…”