Simulation of the temperature field for massive concrete structures using an interval finite element method

Purpose The purpose of this paper is to introduce an interval finite element method (IFEM) to simulate the temperature field of mass concrete under multiple influence uncertainties e.g. environmental temperature, material properties, pouring construction and pipe cooling. Design/methodology/approach Uncertainties of the significant factors such as the ambient temperature, the adiabatic temperature rise, the placing temperature and the pipe cooling are comprehensively studied and represented as the interval numbers. Then, an IFEM equation is derived and a method for obtaining interval results based on monotonicity is also presented. To verify the proposed method, a non-adiabatic temperature rise test was carried out and subsequently simulated with the method. An excellent agreement is achieved between the simulation results and the monitoring data. Findings An IFEM method is proposed and a non-adiabatic temperature rise test is simulated to verify the method. The interval results are discussed and compared with monitoring data. The proposed method is found to be feasible and effective. Originality/value Compared with the traditional finite element methods, the proposed method taking the uncertainty of various factors into account and it will be helpful for engineers to gain a better understanding of the real condition.

Time-Varying Chatter Frequency Characteristics in Thin-Walled Workpiece Milling With B-Spline Wavelet on Interval Finite Element Method

As the most significant material removal method, milling plays a very important role in the manufacturing industry. However, chatter occurs frequently in milling, which will seriously affect the production efficiency. The accurate prediction of chatter frequency can contribute to chatter monitoring and the design of the controller for chatter mitigation. During thin-walled workpiece milling under chatter, a new phenomenon of time-varying chatter frequency is discovered and explained in this paper. This phenomenon can be explained as follows, with the workpiece material removal, the modal parameters change during thin-walled milling, which can cause the continuous change of chatter frequency. In order to predict the varying modal parameters, this paper provided an efficient tool, the B-spline wavelet on interval finite element method (BSWIFEM), which can possess the material removal problem more accurately and more rapidly. Based on the calculated modal parameters, the time-varying chatter frequency can be obtained with the chatter frequency calculation formulas. To verify the calculated results, a number of milling tests are implemented on thin-walled parts. The experimental results show that the calculated chatter frequency is in good agreement with the measured chatter frequency, which validates the effectiveness of the proposed method.