Fracture of solid rocket propellant grains

doi:10.1016/0013-7944(92)90113-S

Engineering Fracture Mechanics

Volume 43, Issue 3, October 1992, Pages 455-459

https://doi.org/10.1016/0013-7944(92)90113-S Get rights and content

Abstract

The importance of fracture criteria in the failure assessment of solid propellant grains is briefly described. Computation of the crack tip stress intensity factor and the development of the crack growth rate equation through fracture properties essential for fracture analysis are also discussed.

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Cited by (15)

Correlation between solid propellant failure and interface debonding in solid rocket motors
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Citation Excerpt :
The function of the liner layer is to achieve good bonding between the propellants and the insulation [3]. Therefore, solid propellants and their interface bonded to the liner layer are two weak parts for the integrity of solid rocket motors [4,5]. The integrity analysis to determine the ultimate failures of the propellants and the propellant-liner interfaces is very important for the prototype design and health condition evaluation of SRMs [6,7].
In the traditional integrity analysis of solid rocket motors, solid propellants failure and propellant-liner interface debonding were intentionally differentiated. This empirical distinction of failure regions based on the macroscopic phenomenon neglects their physical correlation, consequently increasing both experiment quantity and simulation complexity. Here, by experiments and simulations, propellant-liner interface debonding is shown to be induced by propellant breakage, i.e., the substrate failure. In experiments, interface debonding and propellants failure share the same cavitation and stringing processes in crack initiation, and the measured break strain of solid propellants and fracture energy of interface satisfy a similar temperature/strain-rate dependent shifting phenomenon. The finite element model can well predict both the strain field and the stress-strain response of interface debonding by using the parameters calibrated by tensile tests of solid propellants, verifying that interface debonding is induced by propellants breakage. Overall, failure envelopes of both propellants and interfaces satisfy a similar peak-position shifting phenomenon but different peak-value shifting phenomena. The time-temperature superposition of HTPB polymer binders induces the peak-position shift, and strain concentration and relaxation of propellants in the crack front induce the peak-value evolution. This study is promising to unify and simplify the solid propellants failure and interface debonding in the integrity analysis.
Crack propagation velocity and fracture toughness of hydroxyl-terminated polybutadiene propellants: Experiments and simulations
2021, Engineering Fracture Mechanics
Citation Excerpt :
Cracks may propagate rapidly during the launch and cause an unexpected rise in gas pressure that may affect the ballistic performance, even lead to a catastrophic accident. The more specific significance of investigating the fracture characteristics of solid propellants can be found in Ref. [2]. In previous studies, Liu [3–5] studied the fracture characteristics of a highly filled polymeric material at different tensile rates and gave a power-law relationship between the stress intensity factor and crack growth rate.
A critical part of failure analysis in solid rocket motors is understanding the fracture behavior of solid propellants. For single-edge notched tension (SENT) specimens of hydroxyl-terminated polybutadiene (HTPB) propellant, self-developed in-situ video imaging was employed to characterize the crack propagation and the crack-path morphology. Combining this in-situ video recording system with image digitization, then the crack propagation velocity can be obtained. Due to the viscoelastic properties of the propellant, the fracture properties were studied under different tensile rates (5-500 mm/min). A fracture mechanics method based on the J-integral was used to evaluate the fracture behavior of propellants, and a fracture criterion considering the burning rate of the propellant was proposed. Experimental research revealed that the HTPB propellant had a pronounced blunt crack tip during the fracture process. The plastic region in front of the crack tip where voids form and coalesce could cause crack propagation. The distribution of voids in front of the crack tip mainly determined the direction of crack propagation. The fracture characteristics of the HTPB propellant had evident rate dependence, and the J-integral changed significantly under different tensile rates. A simulation study was carried out in this paper. The $1 / r$ singular elements were used to predict the J-integral of the SENT specimen during the tensile process. Two numerical simulation methods (XFEM: extended finite element method and CZM: cohesive zone model) were used to obtain crack propagation velocity and load–displacement curve. Furthermore, the simulation results were compared with experimental data.
Constitutive modeling of porous viscoelastic materials
2007, European Journal of Mechanics, A/Solids
The effect of porosity on the constitutive response of an isotropic linearly viscoelastic solid that obeys a constitutive law of the standard differential form is investigated under small strain deformation conditions. The correspondence principle of linear viscoelasticity is used to solve the viscoelastic boundary value problem at a unit cell containing a spherical void and loaded axisymmetrically by macroscopic stresses. The results are used to devise a constitutive potential for the description of the porous material for any arbitrary combination of hydrostatic and deviatoric loadings, and the associated 3-D constitutive relationship is determined in the Laplace transform domain. Inversion to the time domain yields the constitutive law of the porous material as a function of porosity in the standard form of convolution integrals. The presence of porosity establishes relaxation time scales for the porous body that differ from the relaxation time of the pure matrix material and brings about a viscous character to the overall hydrostatic response. The numerical implementation of the model in a general purpose finite element code is outlined. The model is used to predict the response of a porous solid propellant material in uniaxial tension and cyclic loading at room temperature.
Effect of long-seam mismatch on the burst pressure of maraging steel rocket motor cases
2005, Engineering Failure Analysis
This paper examines the failure bahaviour of maraging steel rocket motor cases to understand the combined stress theories of failure and their use in design. Effects of weld-mismatches on the load bearing capacity of the motor case, failure pressure estimates and their validation through burst pressure testing of the motor case, are discussed. A simplified procedure, which can be easily programmed on a digital computer, is presented for experimental stress analysis through strain gauge measurements on the surface of the casing during test. A simple expression useful for failure pressure estimates of rocket motor cases having weld mismatch, is presented. The failure pressure estimates are found to be in good agreement with the burst pressure test results of maraging steel motor cases.
A comparative study on failure pressure estimations of unflawed cylindrical vessels
2002, International Journal of Pressure Vessels and Piping
There is a need to design a reliable lightweight solid rocket motor case, pressure vessel for a launch vehicle or a missile system. The rocket motor case used in the advanced solid propulsion system is essentially a lightweight shell acted upon by static internal pressure and dynamic and thermal loads during flight, but for practical structural integrity purposes, consideration of internal pressure is all that is necessary. This paper examines existing test data, theories and procedures, frequently used for evaluating the maximum pressure in closed ended cylindrical vessels.
Destructive tests of 15CDV6 steel rocket motor cases and their application to lightweight design
1995, International Journal of Pressure Vessels and Piping

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Technical noteFracture of solid rocket propellant grains

Abstract

Engng Fracture Mech.

Engng Fracture Mech.

Engng Fracture Mech.

Engng Fracture Mech.

J. Metallkde

Fundamental Aspects of Solid Propellant Rockets

Structural integrity analysis of solid rocket motors

The mechanics of polymer fracture

Appl. Mech. Rev.

Pressurised crack behaviour in two-dimensional rocket motor geometries

J. Spacecraft Rockets

Viscoelastic fracture of solid propellants on pressurization loading conditions

J. Spacecraft Rockets

Visco-elastic rocket grain fracture analysis

Int. J. Fracture

On the method of virtual crack extensions

Int. J. numer. Meth. Engng

Finite element crack-tip modelling when evaluating the J-integral

Int. J. Fracture

Explicit expressions for energy release rates using virtual crack extensions

Int. J. numer. Meth. Engng

Modified crack closure integral using six-noded isoparametric quadrilateral singular elements

Engng Fracture Mech.

Technical note
Fracture of solid rocket propellant grains

Finite element crack-tip modelling when evaluating the $J- integral$