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The structural integrity of solid rocket motor(SRM) grain is severely tested owing to the combined action of low temperature and pressure load under the load case of low temperature ignition. The three dimensional finite element model of SRM was created to analyze the structural integrity of the SRM grain subjected to low temperature and ignition pressure based on three dimensional viscoelastic finite element method via MSC.Patran/Marc. Meanwhile, cold pressurization test was applied on certain SRM. The experimental result and numerical result were compared based on uncoupling principal of temperature and pressure. The result show that the safety factor of solid rocket motor grain is 2.46 which can meet the requirement of structural integrity. The experimental results are in good agreement with the simulation results. Relevant research methods and conclusions can provide reference for the design, analysis and test of SRMs.

From the dried root and rhizomes of Atalantia buxifolia afford 11 compounds, one new compound 1 and ten known compounds 2–11 were isolated and identified. The novel compound 1 was alkaloid glycoside. Its mother nuclear was the acridone, which was relatively rare. The structure of compound 1 was established identified by spectrum and elucidated as β-D-Glu-4,5-dimethoxy-1,6-dihydroxy-10-methyl-acridone. The compound 1 enriched the compound library and laid the material foundation for the subsequent study of pharmacological activities. [ABSTRACT FROM AUTHOR]

The viscoelastic Poisson's ratio of solid propellant seriously affects the analytical accuracy of the structural integrity of the solid rocket motor. Based on the digital image correlation (DIC) method, a stress relaxation test and a uniaxial constant tensile rate test were carried out to measure the viscoelastic Poisson's ratio of the composite solid propellant according to the stress characteristics of solidification cooling and ignition pressurization conditions. The effects of time, temperature, longitudinal strain as well as tensile rate on the viscoelastic Poisson's ratio of propellant were studied. In this paper, the main curves of the temperature and strain rate of the propellant Poisson's ratio at the reference temperature of 25 °C and the main curves of temperature and longitudinal strain at the reference time of 10000 s were established. The research shows that the viscoelastic Poisson's ratio of composite solid propellants increased with increasing temperature, longitudinal strain and tensile rate. Under the solidification cooling condition, the Poisson's ratio of the solid propellant does not change significantly with time. At this point, the Poisson's ratio can be regarded as a constant, but the appropriate value must be selected according to the operating temperature and initial deformation of the solid rocket motor. In the uniaxial constant tensile rate test, when the stretching rate reached 500 mm/min, Poisson's ratio of the propellant gradually approached a certain constant value. Considering that the loading rate of the propellant is generally above 0.5 s−1 under the ignition pressurization condition, the strain rate is large, the Poisson's ratio of the propellant can be taken as a constant. Relevant methods and conclusions can provide a reference for structural analysis and storage life prediction of solid rocket motors. [ABSTRACT FROM AUTHOR]

Axial free vibration of a nanobar carrying a nanoparticle is studied based on the nonlocal elasticity theory and Love’s assumption. By considering inertia of radial motion during longitudinal vibration, a governing equation for a nanobar–mass oscillation system is derived via Hamilton’s principle. An exact frequency equation is obtained and an approximate simple expression for the fundamental-mode resonance frequency is given. The size effect of the resonance frequencies is elucidated. The classical Love bar theory and the nonlocal bar theory can be recovered from two special cases by setting the nonlocal parameter and Poisson’s ratio to zero, respectively. Numerical examples are given to show the influence of the nonlocal scaling parameter and attached mass on the resonance frequencies and frequency shifts. Identification formulas for estimating the mass of an attached nanoparticle and predicting the nonlocal parameter are established through the frequency change. [ABSTRACT FROM AUTHOR]

Longitudinal dynamic problems of nanorods or nanobars are analyzed based on the nonlocal elasticity theory and Bishop's assumptions. Radial deformation and inertia are considered. A governing equation for axial motion of circular nanorods is derived via Hamilton's principle. The phase speed of longitudinal waves is determined in explicit form and the dispersion curve is displayed. Exact frequency equations for clamped-free, clamped-clamped, and free-free nanorods are obtained and mode shapes are derived. A unified approximation for low frequencies is given and compared with exact results. The Love theory of nonlocal rods is a special case of the present with shear stiffness vanishing. Classical Bishop and Love rod theories can be recovered only letting the size effect disappear. The simple nonlocal rod model is reduced if setting Poisson's ratio to zero. Illustrative examples of nanofibers and nanotubes are given to show the influence of the nonlocal scale parameter on the phase speed and the natural frequencies. [ABSTRACT FROM AUTHOR]

Context: Since AMP-activated protein kinase (AMPK) activation in skeletal muscle of obese rodents stimulates fatty acid oxidation, it is reasonable to hypothesize that pharmacological activation of AMPK might be of therapeutic benefit in obesity. Objective: To investigate the effects of the traditional Korean anti-obesity drug GGEx18, a mixture of three herbs, Laminaria japonica Aresch (Laminariaceae), Rheum palmatum L. (Polygonaceae), and Ephedra sinica Stapf (Ephedraceae), on obesity and the involvement of AMPK in this process. Materials and methods: After high fat diet-induced obese mice were treated with GGEx18, we studied the effects of GGEx18 on body weight, fat mass, skeletal muscle lipid accumulation, and the expressions of AMPK, peroxisome proliferator-activated receptor άά (PPARα), and PPARα target genes. The effects of GGEx18 and/or the AMPK inhibitor compound C on lipid accumulation and expression of the above genes were measured in C2C12 skeletal muscle cells. Results: Administration of GGEx18 to obese mice for 9 weeks significantly ( p < 0.05) decreased body and adipose tissue weights compared with obese control mice ( p < 0.05). Lipid accumulation in skeletal muscle was inhibited by GGEx18. GGEx18 significantly ( p < 0.05) increased skeletal muscle mRNA levels of AMPKα1 and AMPKα2 as well as PPARα and its target genes. Consistent with the in vivo data, GGEx18 inhibited lipid accumulation, and similar activation of genes was observed in GGEx18-treated C2C12 cells. However, compound C inhibited these effects in C2C12 cells. Discussion and conclusion: These results suggest that GGEx18 improves obesity through skeletal muscle AMPK and AMPK-stimulated expression of PPARα and its target enzymes for fatty acid oxidation. [ABSTRACT FROM AUTHOR]

A probabilistic storage life prediction model of solid rocket motor (SRM) grain is proposed based on the viscoelastic stochastic finite element method (SFEM) and the temperature accelerated aging test of solid propellant. The relationship between the digital characteristics of solid propellant property parameters of solid propellant and storage time is derived from the statistical analysis of aging test data, and the mean and standard deviation of grain structural response are calculated using 3 D viscoelastic response surface SFEM. The structural reliability of a certain SRM grain at the different storage times is analyzed, and its probabilistic storage life is estimated. The methods are available for the designers and users of SRM. [ABSTRACT FROM AUTHOR]