Applied Mechanics and Materials Vols. 117-119

Abstract: Experiment investigation of mechanical, physical, and biological properties on a dental precious alloy was performed. The density of the alloy is 12.04 g/cm³, the solidus temperature is 1144.5 °C and the liquidus temperature is 1283.5 °C. The coefficient of thermal expansion of the alloy is 14.84×10^-6 /°C between 25 °C to 500 °C. The average 0.2% yield strength is greater than 400MPa, and the average percentage elongation after fracture is greater than 4%. The average bonding strength of the metal-ceramic is 41.93 MPa, much greater than the standard requirement. The biocompatibility of the alloy is excellent, there are no cytotoxicity reactivity, sensitization, irritation, mutagenicity and short-term systemic toxicity. The alloy is a superior dental alloy with excellent mechanical, physical and biological performance.

Abstract: This work is concerned with the dispersion characteristics of Love waves propagating in a layered structure consisting of an anisotropic elastic layer and a piezoelectric half-space. The layer processes one symmetric plane, while the half-space is transversely isotropic. The explicit dispersion equation is derived. As an example, an inclined orthotropic material is chosen as an elastic layer to reveal the effect of material anisotropy on the dispersion behaviors. The numerical results show that the phase velocity is strongly influenced by the anisotropic degree.

Abstract: Stereolithography technique is dealt with the techniques of machinery, laser, numeral control, computer software and photosensitive resins, etc. The quality of the photosensitive resins has direct effect on the dimensional accuracy, mechanical properties of the fabricated parts. Therefore the further research on SL7560 type photosensitive resins is very meaningful and valuable. The properties of SL7560 type photosensitive resin were investigated by some instruments and equipments. Characteristics of FT-IR showed that SL7560 type photosensitive resin belonged to an epoxy-acrylic hybrid photosensitive resin. The experimental results showed that its viscosity at 30°C was 197mPa.s, its critical exposure (E_c) was 5.9mJ/cm2, its penetration depth (D_p) was 0.14mm, the tensile strength of its cured product was 43.7MPa, the tensile modulus was 2549MPa, the elongation at break was 10.7%. With the photosensitive resin as the processing material, the part of a mobile phone shell was fabricated using the Stereolithography Apparatus (HRPL-I), and the quality of the fabricated part was good.

Abstract: The short term tensile creep behaviors of polypropylene (PP) packaging belt under different stresses levels were studied through tensile creep test. The four-element model was applied to simulate the creep behaviors of the PP packaging belt. The results show that four-element model can be used to simulate the short time creep of PP packaging belt. The tensile creep behaviors of PP packaging belt have obviously correlation to the stress levels. The instantaneous elastic coefficient, delayed elastic coefficient and glutinous coefficient in Maxell model show a decreasing tendency with the increase of stress level. Based on the time-temperature-stress equivalence principle and take 15% stress level as a reference, the creep compliance master curve of 15% stress level was constructed by horizontal shift of the creep compliance curve of other stress levels, which can predict the creep behavior of PP packaging belt at the 15% stress level.

Abstract: Abstract. Based on the newly developed homogenization theory of masonry, homogenization model of masonry is built in this paper. And a failure criteria adapation to masonry homogenization units is suggested union finite element analysis result of homogenization model.

Abstract: Mechanical properties have close relation with microstructure. Based on orientation of the molecule chain in fiber, they show a rapid increase in tensile properties. Nevertheless, block materials mainly gain rise of mechanical properties by blend or composite, it is hardly proposed on the self-reinforced materials by optimizing the microstructure. In this work, the structure and tensile properties of polypropylene (PP), treated at 105°C for 5min under different pressure, were studied with microscopy, differential scanning calorimetry (DSC). The variety of supra-structure that the spherulite deforms into ellipse even fractures piece in the pressure field adds to the mechanical properties. The orderliness of crystal increases with the pressure, and Tm is increased slightly from the original level.

Abstract: Slope protection with vegetation is a new technology which is using vegetation to preserve water and soil, so reduce slope instability and corrosion, simultaneously beautify ecological environment. Using vegetation for slope protection can protect slope, and can overcome the shortcoming of traditional slope protection ways.This article takes Northeast Forestry University tree farm as an experimental field. According to climatic conditions of northeast area, soil texture conditions of highway slopes and other conditions, this text selects 6 different common herbs to plant, observes ecology compatibility and preserving soil ability of each kind of plant, then uses mathematical method to appraise slope protection effect of each kind of plant.Results indicate that different type of grass has different slope protection effect.

Abstract: It is of great importance to innocuity, minimization and reutilization of manganese slag generated in manganese product by electric furnace process. In the paper, ordinary Portland cement was replaced partly by manganese slag to then evaluate manganese slag’ effect on mechanical performances of them. The experimental results obtained show that ordinary Portland cement added less than 30% by manganese slag was improved in mechanical performances and the cement concrete added less than 30% by manganese slag was not changed significantly. To lower economic cost and achieve enhanced mechanical performances, manganese slag can be substituted partly to cement concrete.

Abstract: A novel Shrinkage reducing admixture (SHSRA) has been developed. Several tests including the workability , drying shrinkage，the hydration heat and strength tests were carried out to evaluate the effect of SHSRA on the performance of the concrete specimens. The results showed that the presence of SHSRA induced a significant reduction in dry shrinkage by up to 40% after 28 days. The SHSRA could cause decreases in both hydration rate and heat release of hydration of cementing materials which can attribute to reducing the risk of cracking. Besides, no negative side effect on the concrete workability and the later strength has been observed with the addition of the SHSRA.

Abstract: Hydrogen desorption temperature of MgH₂, which was milled with 20 pieces of ZrO₂ balls for 20 h, was decreased to 240 °C, although steel−ball−milled MgH₂ required more than 350 °C. Moreover, the completely dehydrogenated product was able to absorb hydrogen of ~3.5 mass% even at room temperature under 1 MPa hydrogen within 5 hours. Inductively coupled plasma−atomic emission spectroscopy analysis revealed zirconium element was doped into MgH₂ from the ZrO₂ balls during the milling process. Therefore, it was concluded that the presence of ZrO₂ improved the kinetics of the hydrogenation and dehydrogenation behaviors of MgH₂.