Experimental and simulation research on microscopic damage of HTPB propellant under tension-shear loading

Abstract

In order to study the influence of loading conditions on propellant mesoscopic failure morphology, scanning electron microscopy was carried out to observe the morphology of the failure section of a hydroxyl-terminated polybutadiene propellant under different temperatures, loading speeds, and loading conditions. Using the finite element method, a mesoscopic model of a composite solid propellant was constructed, and the mechanical parameters of the propellant particle–matrix interface were obtained based on the parameter inversion method. A meso-model of a hydroxyl-terminated polybutadiene propellant under different loading conditions was constructed, and numerical results were compared with experimental results to analyze the meso-damage. With decreasing temperature and increasing loading speed, the level of propellant damage increased, and the particle–matrix interface became more prone to damage under the combined action of tensile and shear loads. In addition, with an increasing loading angle, ammonium perchlorate particles were more prone to dewetting.

Mechanical properties and influence mechanism of hydroxyl‐terminated polybutadiene propellant under confining pressure

“…In order to describe the mechanical properties of interfaces, the bilinear cohesive zone model (BCZM) was introduced in this work due to its highly efficient and simple formula. 18,35,[37][38][39] The BCZM theory assumes that interface mainly goes through three stages: (1) elastic stage: interface stress has a linear increasing relation with opening displacement; (2) Damage softening stage: when interface stress reaches maximum strength, interface damage would germinate and evolve. At this stage, interface stress decreases linearly with the increase of opening displacement; (3) Failure stage: when opening displacement reaches critical failure value, interface stress drops to zero and interface completely fails.…”

“…Reference [37] shows the E 0 = 5 MPa and of composite matrix at room temperature, so the Neo‐Hookean hyper‐elastic model parameters can be calculated as C 10 = 0.836 MPa and D 1 = 0.012 MPa −1 based on the Equations ().…”

“…The bonding mechanical properties of filler particles‐matrix interfaces have the most significant influence on the macro mechanical properties of solid propellant, and they are the weakest link of integrity of solid propellant. In order to describe the mechanical properties of interfaces, the bilinear cohesive zone model (BCZM) was introduced in this work due to its highly efficient and simple formula 18,35,37–39 . The BCZM theory assumes that interface mainly goes through three stages: (1) elastic stage: interface stress has a linear increasing relation with opening displacement; (2) Damage softening stage: when interface stress reaches maximum strength, interface damage would germinate and evolve.…”

Study on Mechanical Properties and Failure Mechanisms of Highly Filled Hydroxy-Terminated Polybutadiene Propellant under Different Tensile Loading Conditions

“…This criterion assumes that the fracture of the material is caused by the maximum tensile stress. The damage of solid propellant is mainly caused by three conditions: particle fracture, matrix tearing, and interfacial damage (dewetting) [41]. In the actual failure process, the three damage modes are not individual, but various damage modes interact with each other and are coupled, often forming a complex damage mechanism.…”

“…As can be seen from Figure 12, the microscopic fracture morphology of propellant formed under different loads is different, which indicates that the failure mechanisms of the propellant are different under different strain rates. The damage of solid propellant is mainly caused by three conditions: particle fracture, matrix tearing, and interfacial damage (dewetting) [41]. In the actual failure process, the three damage modes are not individual, but various damage modes interact with each other and are coupled, often forming a complex damage mechanism.…”