不同锁模机构注塑机胀模特性的研究

系统研究了直压式和肘杆式注塑机的胀模特性以及注射压力和注射时间对胀模量的影响,并考察了胀模量与制品质量之间的关系。结果表明,不同的锁模机构具有不同的胀模特性,胀模量与制品质量之间呈现线性关系,胀模量越大,制品的质量越大;注塑机的注射压力和注射时间对胀模量有很大的影响;注射压力越大,胀模量越大;注射时间越长,胀模量越大。

肘杆式全电动注塑机胀模特性实验研究

注射成型过程中由于型腔压力大于锁模力而产生的胀模现象对注塑制品质量具有显著的影响。基于全电动三板肘杆式注塑机,系统研究了注射成型过程中的胀模特性和由胀模引起的锁模力变化特性。结果表明,在肘杆式注塑机的胀模过程中,锁模力变化量能够反映胀模程度的大小,锁模力最大增量与锁模力变均可作为衡量注塑制品质量的指标。

Swelling characteristics of East-Africa black cotton soil based on computer molecular simulation

Black cotton soil in East Africa is not a stable engineering material for highway and railroad projects. Its strong swelling potential when it absorbs water causes distresses in subgrade of highway and railroad, and thus leads to failures of the projects. This paper presents study on the swelling characteristics of black cotton soil in East Africa. Lab tests were conducted to obtain its basic engineering properties, and the results show that black cotton soil contains high amount of montmorillonite and exchangeable cations and is strong expansive soil. Molecular modelling was exploited to further investigate water absorption ability of montmorillonite. Three different molecular models of montmorillonite were constructed and used for simulations, among which Types I and II montmorillonite represent the expansive soil montmorillonite in China, and Types II and III montmorillonite represent black cotton soil montmorillonite in East Africa. The results showed that the interlayer cations of Type III montmorillonite possessed the strongest water absorption ability based on analysis of radial distribution function(RDF) of cations. Interlayer compensatory cations of Na+ enhance the hydration ability of the other major cations, thus resulting in the strong swelling potential of East-Africa black cotton soil.

Combination effect of seasonal freezing and artificial freezing on frost heave of silty clay

To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.

Clay mineral expansion of black cotton soil based on interlayer cation hydration

To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic boundary.Results indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water molecules.The exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.

Identifying storm-induced wave origins using SAR wave mode data

Because of weak dissipation effects, swells generated by fierce storms can propagate across an entire ocean basin;therefore, observing swell generation and decay and retrieving storm characteristics from a swell by satellite remote sensing are possible. In this study, based on the dispersion relation and geometrical optics principle, we used SAR wave mode data from 2003 to 2010 provided by GlobWave to track swells with peak wavelengths of more than 300 m to locate a storm-generated far-traveling swell and present the swell field related to this "static" origin. Through a comparison with ECMWF wind datasets, we conducted validations and explored some conditions that cause misjudgments in swell origins. Finally, we obtained the spatiotemporal distribution characteristics of satellite-observed swell origins(i.e., the fierce wind condition) and their evolution. This work can be used as a reference for wave models, providing early swell warnings, determining air-sea surface interactions, and determining global climate change.