Papers by Keyword: Shell

Abstract: This paper presents an efficient finite element modeling technique for stiffened composite shells having different stiffening arrangements. The laminated shell skin is modeled with a triangular degenerated curved shell element having 3 corner nodes and 3 mid-side nodes. An efficient curved beam element compatible with the shell element is developed for the modeling of stiffeners which may have different lamination schemes. The formulation of the 3 nod degenerated beam element may be considered as one of the major contributions. The deformation of the beam element is completely defined in terms of the degrees of freedom of shell elements and it does not require any additional degrees of freedom. As the usual formulation of degenerated beam elements overestimates their torsional rigidity, a torsion correction factor is introduced for different lamination schemes. Numerical examples are solved by the proposed finite element technique to assess its performance.

Abstract: In order to study the maximum strain of steel shell surface under the impact of a falling ball, a thin shell model and the strain time history curves of impact are achieved by ANSYS/LS-DYNA. A deformation behavior of the shell was calibrated from the test which uses a ball free fall and some resistance strain gauges pasted to the inner surface of an iron shell box. The gauges are connected as inputs to a Wheatstone bridge circuit and an Oscilloscope is used to observe the output. The results show the impact test and ANSYS/LS-DYNA simulation results are smoothly consistent with the strain of the test at the maximum strain amplitude of the model, and the maximum difference is 9.5%. Accurate results can be achieved by combining the test method and the simulation approach as an industrial application.

Abstract: MEMS gyroscope can be used in various field such as stabilization, controlling and guiding, navigation and so on. Bias variation over temperature is the key performance in MEMS gyroscope. The encapsulation moisture has great influence on the bias variation of MEMS gyroscope.By experiments on gas recharged, roast temperature, die attach adhesive and encapsulation shell, method to depress the encapsulation moisture is obtained. By DPA, the encapsulation moisture of sensing element encapsulated by the reformative method can be reduced to less than 1000 ppm, and the performance on temperature of MEMS gyroscope is improved.

Abstract: According to the problem that the thickness change of the square cylinder as energy-absorption component affect energy-absorption characteristics of the square cylinder, this paper researches that the thickness of the square cylinder for energy-absorption component of the square cylinders influence through theoretical analysis and using numerical calculation method. The theoretical part in this paper analyze local deformation of the square cylinder theoretical model as a result of axial compression ,and in the numerical simulation part this paper simulate the dynamic response of the thin wall square cylinder model structure , thereby research the thickness change of the square cylinder influence on energy-absorption characteristics of the square cylinder. At last, the change curve of the force-deformation is drawn with the change curve of force-peak load, and it is obtained law that the thickness of the square cylinder influence on energy-absorption characteristics the square cylinder and optimum thickness.

Abstract: Phosphorus removal from wastewater has always been given serious attention in sewage treatment. Eutrophication can happen if phosphorus wastewater is directly discharged into natural water and high phosphorus-contained irrigation water may lead crops beat down. The research investigated the phosphorus removal efficiency in wastewater by shell powder. The experiment results showed that the best removal effect could meet the Wastewater Treatment Plant Discharge Standard (GB18918-2002) Grade I-A in China, which can be achieved under the conditions of the dosage of shell powder solution 1 ml, pH > 11 and precipitation one to four hours at the initial phosphorus concentration of about 3 mg/L.

Abstract: The article considers the influence of neutron flux on the reactor hemispherical shell protection, depending on time. Diagrams of the variations of modulus of elasticity, of strain and stress appearing during the operation of the nuclear power plant are given.

Abstract: The free vibration characteristics of the prestressed joined spherical–cylindrical shell with free-free boundary conditions are investigated. The Flügge shell theory and Rayleigh-Ritz energy method are applied in order to analyze the free vibration characteristics of the joined shell. In the modal test, the LMS software is used to calculate mode shapes and natural frequencies of the joined shell structure. The natural frequencies and mode shapes are calculated numerically and they are compared with those of the FEM and modal test to confirm the reliability of the analytical solution. The effects of the shallowness and length of the cylindrical shell to the free vibrational behavior of joined shell structure and the effect of internal pressure on the modal charactristics are investigated.

Abstract: The paper presents the research report studied at the largest natural gas producer and the petroleum retail market leader in Malaysia. The study is to understand the logistics performance measurement in the supply chain, including the theoretical discussion on data collected and logistic performance of a real organization using the balanced scorecard. Besides that, the study will also access the performance of the company and followed by identifying the problems and provides recommendations for improvements.

Abstract: The application of perforated shell gradually increased, but the current design method has no explicit provisions. In this paper, based on large depth-to-span ratio and openings of single-layer spherical lattice shells structure for static and dynamic analysis, and the effects of opening and not opening shell difference of internal force under static load and deformation, I put forward the design proposal.

Abstract: In the present work, shell, which is available in abundance, low cost and non-toxicity, was used as a source of calcium for preparation of heterogeneous base catalysts. The catalyst was prepared by dissolution-precipitation method in which a calcined shell was mixed with Zn(NO₃)₂ and Al₂O₃ under acidic conditions, followed by calcination at 300-700 °C. ZSA-I was referred to as the catalyst attained under the suitable synthesis conditions. Physicochemical properties of ZSA-I were studied by using X-ray fluorescence spectroscopy (XRF), powder X-ray diffraction (XRD), thermogravimetric/ differential thermal analysis (TG/DTA) and CO₂-pulse chemisorption analysis. ZSA-I gave the highest fatty acid methyl ester yield of 99 wt.% in the transesterification of palm oil with methanol and can be reused at least 5 times with a retention of the methyl ester yield higher than 96 wt.%.