Meso Propellant Bonding Interface Mechanics Model And Parameter Acquisition Methods

In consideration of the fact that the HTPB propellant is filled up with a plenty of solid particles, the mechanical property of the adhesive interface in the inner micro-structure of propellant is dedicated enough to influence the integral property of it. In order to understand the bonding situation between particles and matrix better, to express the mechanical property of the bonding interface better, a systematic research towards to the micro adhesive interface mechanical model of propellant was established, which is divided into4parts as follows,1. The experiment methodology and the specimen preparation of the micro bonding structure of propellant. Referring to the relevant science paper and standards, a feasible experiment plan is made in conjunction with the specific feature of the research object and the available means, i. e. obtain the cohesive interface fracture energy with Al/HTPB bonded DCB test, obtain the cohesive strength of the interface through Al/HTPB uniaxial debonding test, identify the visco-hyperelastic property of the HTPB adhesive with uniaxial test which applied to the solidified HTPB adhesive. The specimens were prepared for tests.2. The rate-independent cohesive zone model (CZM) and the method for obtaining the parameters. With the Al/HTPB bonded DCB test which indicated mode I fracture of the interface, the property of interface fracture was analyzed. A bilinear CZM was constructed to express the interface property. The parameters were obtained with the segment inversion identification method and fracture mechanism method, respectively, and a comparison was made between them, indicating that the parameters obtained by inversion identification method can better reflect the adhesive property of the material. The reason for the inaccuracy of the fracture energy parameters derived with classic beam theory was analyzed. The results of the Al/HTPB uniaxial debonding test showed a good accuracy of the model and the parameters obtained with it, also indicated a good agreement between the built CZM and the forecasted adhesive surface of the specimen.3. The construction of the rate-dependent CZM. To express the rate-dependency of the interface, a new rate-dependent CZM was built. The model consists with a rate-independent CZM and a rate-dependent Maxwell element, which parallel to each other. The equation of the constitutive model and whose increment form were derived by substituting parameters, and an analysis was established to evaluate the rate-dependency of the new model. Ultimately, an investigation was made to adopt the new method in the finite element software, i.e. a UMAT subroutine of finite element software Abaqus(?) was established.4. The method of obtaining the rate-dependent CZM parameters. With the uniaxial debonding test under various rates, the discipline of the cohesive strength of the interface is obtained, the topographic characteristics were analyzed under different moments of the test. In contrast to the uniaxial test carried on the solidified HTPB test, the properties of the HTPB under different status were analyzed. The mode I fracture rate-dependent property of the interface was obtained by the uniaxial tests with Al/HTPB DCB specimen under different test rates, the fracture process and the micro and macro properties were analyzed. The parameters were obtained with the inversion identification method and fracture mechanism method, respectively, and a comparison was mode between them.In this paper, the adhesive property of the Al/HTPB interface was obtained with the method of combining experiment and numerical simulation. An interface model which is capable of expressing the property of the material was built, together with the parameter obtaining method. The study made a theoretical basement and reference accordance to the micro-structure mechanical of propellant, and an insight to the further study of the integral mechanical property of the solid propellant.