Search results

This paper aims to identify the role of the wall slip on the dynamic characteristics of the multi-groove water-lubricated bearing considering rough contact, including stiffness and damping coefficients of the water film and contact stiffness coefficient of the asperity contact.

The modified perturbed average Reynolds equations with the wall slip are derived, and the calculated perturbed hydrodynamic pressures are integrated to obtain the stiffness and damping coefficients of the water film. The elastic-plastic contact model of Kogut and Etsion is used to determine the contact stiffness coefficient.

Numerical results reveal that the wall slip has the more significant impact on the water film stiffness coefficients compared with the damping and contact stiffness coefficients. When the slip angle lies in a reasonable range, the lubrication performance can be effectively improved, especially in the mixed lubrication condition. In addition, it is worth emphasizing that the abrupt change of the water film stiffness coefficients occurs at the region II (pressure zone) in this study.

The influence mechanism of the wall slip on the dynamic characteristics of the water-lubricated bearing considering rough contact is first revealed.

The purpose of this paper is to establish a combined model for selecting key indexes of complex equipment, and then improve the cost forecasting precision of the model. The problem how to choose the key elements of complex products has always been concerned on many fields, such as cost assessment, investment decision making, etc.

Using Grey System Theory to establish a cost estimation model of complicated equipment is more reasonable under the few data and poor information. Therefore, this paper constructs cost index’s system of complex equipment, and then quantitative and qualitative analysis methods are utilized to calculate the grey entropy between the characteristic parameter and the behavior parameters. Further, establish the grey relational clustering matrix of the behavior sequences by using the grey relative incidence analysis. Finally, the authors select key indicators according to the grey degree.

The experiment demonstrates that the cost key parameters of complex equipment can be successfully screened out by the proposed approach, and the cost estimation accuracy of complicated products is improved.

The method proposed in this paper could be utilized to solve some practical problems, particularly the selection of cost critical parameters for complex products with few samples and poor information. Taking the cost key indexes of civil aircraft as an example, the results verified the validity of the GICM model.

In this paper, the authors develop the method of GICM model. Taking the data of civil aircraft as an example, the authors screen the key indicators of complex products successfully, and improve the prediction accuracy of the GM (1, N) model by using the selected parameters, which provides a reference for some firms.