Non-linear analyses of the preforming process of a multilateral junction assembly are reported in this paper and plasticity and geometric non-linearity including large deformation have been accounted for. A circular arch with both longitudinal sections being built-in and compressed laterally by a rigid elliptic hold-down plate is studied first. A rigid-perfectly plastic model is adopted and a collapse mode is proposed. By analysing the relationships between loading and deformation under each collapse mode, the incipient collapse load and force-deflection curve for the circular arch are presented. The relation between compressing force and deformation during preforming process of multilateral junction assembly is then obtained by integrating along the multilateral leg longitudinally. The research will provide guidance for structural design of multilateral tools and for application of multilateral well technology.
In this paper, the CFD (computational fluid dynamics) model is established
for the low voltage winding region of an oil-immersed transformer according
to the design parameters, and the detailed temperature distribution within
the region is obtained by numerical simulation. On this basis, the RSM
(response surface methodology) is adopted to optimize the structure
parameters with the purpose of minimizing the hot spot temperature. After a
sequence of designed experiments, the second-order polynomial response
surface and the SVM (support vector machine) response surface are
established respectively. The analysis of their errors shows that the SVM
response surface can be better used to fit the approximation. Finally, the
PSO (particle swarm optimization) algorithm is employed to get the optimal
structure parameters of the winding based on the SVM response surface. The
results show that the optimization method can significantly reduce the hot
spot temperature of the winding, which provides a guiding direction for the
optimal design of the winding structure of transformers.
It is very important to process acid and fracturing treatment in oil field to improve permeability. The fracturing pump is one of the key equipment for Acid and fracturing treatment. The valve box of fracturing pump is fundamental, costly and wearing parts. Based on the data from domestic and abroad, the life of the valve box is short. Fatigue cracks caused by alternating stress and erosion account for the most invalidation of the valve box. Only increasing structural size and improving material property are not efficient to prolong service life. Related studies show that hydraulic self-enhancement technology is an effective method and it is used widely to improve service life of fracturing pump’s hydraulic parts. Here hydraulic self-enhancement process was simulated by finite element method and 600 Horse Power fracturing pump was studied. The optimal self-enhancement pressure and loading-unloading treatment method are suggested. This study offers a method to found valve box's production technics by hydraulic self-enhancement technology.
In this paper, a coupled flow-thermal field simulation model is established
based on the parameters of the transformer. Then the distribution of the
flow and thermal fields are obtained. The results show that oil backflow
occurs to varying degrees at the top and bottom of the transformer. In
addition, with the formation of backflow, the hot spot temperature of the
transformer increases. Through the combination of orthogonal experiments and
finite element method, the geometric structure of winding oil passage is
selected as the optimization variable. The law between the winding structure
and the maximum temperature is acquired by means of range and variance
analysis, and the optimal parameters are obtained. The hot spot temperature
is reduced by 34.27 K compared to the pre-optimization period, which is a
guideline for the design of transformers.
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