General Expansion-Temperature Equation

Abstract

This paper presents a continuous, multilinear expression that can be used as a general expansion-temperature equation. The equation can accommodate an unlimited number of connected linear portions. Therefore, it can be easily adapted to represent the expansion behavior of materials—including those of steel, the behavior of which changes abruptly with temperature during phase transformations. Being a continuous curve, it has a major advantage over other comparable expressions, in that all the parameters in the equation can be determined simultaneously in a single curve-fitting operation. Consequently, it can be useful and powerful for characterizing test results. This paper also shows examples where the equation is fitted to experimental data obtained from various grades of structural steel. The examples show that a curve with four linear portions is sufficient to closely fit the test data. Accordingly, a model is constructed for representing the expansion-temperature behavior of structural steel. This model is also presented in this paper.