Constitutive modeling of solid propellants for three dimensional nonlinear finite element analysis

To study the tensile mechanical properties of the Nitrate Ester Plasticized Polyether (NEPE) propellant under varying confining pressure conditions, uniaxial tensile tests were conducted under different strain rates (from 0.0006667 s−1 to 0.06667 s−1) and confining pressure conditions (from relative atmospheric pressure up 5.4±0.03 MPa) using a new‐designed confining pressure testing machine. Scanning electron microscopy (SEM) was employed to observe the tensile fracture surfaces. The mechanical properties and damage processes of the NEPE propellant under varying confining pressure conditions were studied and analysed. The results indicate that the mechanical properties of propellant materials are remarkably influenced by the varying confining pressure conditions. The ultimate strain and maximum tensile stress increase with increasing confining pressure. Moreover, the maximum tensile stress present a linear‐log relationship with the strain rate under various confining pressure conditions. Yet, the confining pressure has no obvious effect on the initial elastic modulus. The reason for the change of the mechanical properties of the NEPE propellant is that confining pressure delays the initiation and development of damage under the tensile loading. Based on the time‐pressure superposition principle (TPSP), the master curve of maximum tensile strength of the NEPE propellant was constructed. Furthermore, the results can provide a theoretical foundation for the analysis of the structural integrity of propellant grains of a SRM under ignition conditions. Finally, a constitutive model considering compressibility of propellant materials can be constructed.

“…Recently, Tunç et al. [19, 20] proposed three‐dimensional constitutive models and implemented the models in a finite element software (ABAQUS). The effects of pressure were considered.…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on Tensile Mechanical Properties of NEPE Propellant under Confining Pressure

Wang

Meng³

et al. 2020

“…Under storage and transportation conditions, the reliability of solid propellant rocket motors must be considered carefully, especially the degradation of the structural capability of the propellant must be investigated and controlled within a certain range [19]. Three-dimensional constitutive models were proposed to explain the mechanical phenomena of solid propellants, and then implemented in finite element analyses [20][21][22]. In these studies, the viscoelasticity and damage were considered but the fatigue life was not considered.…”

Section: Introductionmentioning

confidence: 99%

Study on the Viscoelastic Damage Properties of NEPE Solid Propellant with Different Cyclic Stress Ratios

Fang

Sha³

et al. 2022

Viscoelastic damage properties of NEPE (Nitrate Ester Plasticized Polyether) solid propellant have been studied in this work. This work focuses on the creep and fatigue damage evolution. Cyclic loading tests for NEPE solid propellants are conducted with different stress ratios. Then a modified model incorporating viscoelasticity and damage evolution is presented and used to fit the experimental data. The fitting results show that the model is suitable to characterize the viscoelastic damage properties of NEPE propellants with different stress ratios. Based on the model with parameters for NEPE propellants, the damage parameter D are obtained. The damage evolution curves under different loading conditions are given. It is shown that, from the predicted damage evolution curves, the critical damage parameter Dcr at the fracture points can be used to predict the fatigue lives under different loading conditions.

“…To represent the effect of pressure on the stress‐strain properties, Özüpek [29] proposed to incorporate the pressure on the volume dilatation by an exponential multiplier containing pressure term directly. Furthermore, Canga [30] and Tunç [31, 32] modified and implemented it into a commercial software ABAQUS as a user material. According to the finite strain constitutive model framework and Park's experimental results, Kumar et al.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Hou

et al. 2021

In order to study the effects of confining pressure and strain rate on the mechanical properties of the Nitrate Ester Plasticized Polyether (NEPE) propellant, compressive tests were conducted under various confining pressure conditions and strain rates using a new‐designed active gas confining pressure testing machine. The stress‐strain curves and mechanical properties of the NEPE propellant under varying confining pressure conditions and strain rates were obtained. The results show that the compressive mechanical properties of the NEPE propellant are remarkably influenced by the confining pressure and strain rate. The compressive strength under confining pressure is obviously larger than those without applied confining pressure. With the coupled effects of the confining pressure and strain rate, the compressive strength under 5.4 MPa and 6.67×10−2 s−1 is 2.17 times of its value at room condition and 6.67×10−4 s−1. Then, based on previous tensile results, the quantified comparisons of tensile and compressive mechanical properties under different experimental conditions were presented. Finally, a nonlinear constitutive model with damage was constructed to model the effect of pressure. The statistical damage model parameters were defined as ExpDec1 function of pressure P. The calibrated model can accurately predict the mechanical behaviour of the NEPE propellant under different confining pressure conditions and strain rates.