Dynamic Mechanical Response and Damage Mechanism of HTPB Propellant under Impact Loading

Abstract

<jats:p>The dynamic mechanical behaviors of Hydroxyl-terminated polybutadiene (HTPB) propellant was studied by a split Hopkinson pressure bar apparatus (SHPB) at strain rates ranging from 103 to 104 s−1. The obtained stress–strain curves indicated that the mechanical features, such as ultimate stress and strain energy, were strongly dependent on the strain rate. The real time deformation and fracture evolution of HTPB propellant were captured by a high-speed digital camera accompanied with an SHPB setup. Furthermore, microscopic observation for the post-test specimen was conducted to explore the different damage mechanisms under various conditions of impact loading. The dominated damage characteristics of HTPB propellant were changed from debonding and matrix tearing to multiple cracking modes of ammonium perchlorate (AP) particles, along with the increase of the strain rate. For the first time, the influence of AP particle density on the dynamic response of HTPB propellant was studied by analyzing the strain-rate sensitivity (SRS) index of HTPB propellant with two different filler content (80 wt.% and 85 wt.%), which deduced from a power function of ultimate stress and strain energy density. The result of this study is of significance for evaluating the structural integrity and security of HTPB propellant.</jats:p>

Viscoelastic Properties of Inert Solid Rocket Propellants Exposed to a Shock Wave

“…Inclusion of a damage model (e. g. cohesive zone model [51, 52, 53]) will be considered in the future to facilitate the prediction of the debonding behavior of the particles embedded in the HTPB matrix caused by large deformations. The cohesive zone models will account for the damage in the bulk response that is caused by the local (microstructural) fracture due to each particle separating from the surrounding matrix [13], which would improve the fit of the iFEA and DIC and result in a lower .…”

“…Structural integrity is further compromised when the HTPB propellant is mechanically loaded multiaxially, during storage and/or the ignition and firing process of the solid rocket propellant [5,8,11]. Mechanical loading causes interfacial debonding (i. e. dewetting) of the particles that are bonded to the matrix, which leads to damage of the solid rocket propellant [12,13]. The damage manifests as cracks in the HTPB propellant, which affects the ballistic performance of the solid rocket propellant and the structural in-tegrity of the solid rocket motor [14].…”

The Out-of-Plane Compression Response of Woven Thermoplastic Composites: Effects of Strain Rates and Temperature

“…In order to assess the effect of strain rate on the out-of-plane dynamic compressive properties of thermoplastic composites, a well-known Backofen formula [ 40 ] was applied to analyze the experiment data: where denotes stress, is strain rate, is an intrinsic parameter of the composite, and is the strain-rate-sensitivity (SRS) index expressed as …”

“…In addition, the strength, modulus, and failure strain of CF/PPS composites increased approximately linearly when strain rate increased from 717 to 3414/s. In order to assess the effect of strain rate on the out-of-plane dynamic compressive properties of thermoplastic composites, a well-known Backofen formula [40] was applied to analyze the experiment data:…”

The Influence of the Level of Load in the Mixer on the Processability and Mechanical Properties of the Solid Composite Propellant

“…Solid composite propellant has been widely used in solid rocket motors (SRMs) and missiles due to its high energy density, good processability, and mechanical properties [1][2][3][4][5]. The mechanical properties are relevant on the evaluation of solid composite propellants because they must have good properties to support the different efforts during their useful life.…”