Evaluation of magnetic flux leakage signals on fatigue crack growth of mild steel

Abstract

In engineering applications, analysis of crack growth life is useful in situations where an unexpected crack has been found in a component of a machine, vehicle, or structure. The objective of this research is to investigate the correlation curve of magnetic flux leakage, Hp(y) signals by evaluating their critical value point with respect to step size. Moreover, the relation of fatigue crack growth rate, da/dN toward the stress intensity range, ΔK and Hp(y) in metal components is also discussed in this paper. The tension-tension fatigue test was conducted with the metal magnetic memory scanning device and crack opening displacement (COD) gauges in 10 Hz (testing frequency) by applying a load for 3.0-5.0 kN respectively. As a result, the correlation curve of Hp(y) was built with the R-Squared values in the range of 0.99 and one mathematical model has been developed for estimation analysis. The sigmoidal shape curve was plotted on the graph of da/dN versus ΔK and also with Hp(y). Thus, for validation, the linear relation is represented between ΔK and Hp(y) that present a good approach for magnetic parameter to be developed in the fatigue crack growth analysis. Therefore, the magnetic method has greater capability to analyze the fatigue crack propagation life in a real application.

Magnetic flux gradient observation during fatigue crack propagation: A case study of SAE 1045 carbon steel used for automotive transmission parts

“…As displayed, the pattern of this plot is similar to that of the second region in Figure 2 Hypothetically, dH(y)/dx and ∆K are similar in the sense that they both indicate the state of stress during fatigue crack growth. Xing et al [11] and Ahmad et al [19] investigate relationship between ∆K and H(y) and it was stated that H(y) variation reflects the change of stress intensity factor ∆K during the whole crack growth process and linear relation was represented between ΔK and H(y) graph. Figure 6 illustrates the investigation conducted on the relationship between dH(y)/dx and ∆K.…”

Fatigue crack growth analysis on square prismatic with embedded cracks under tension loading

“…In addition, a study related with numerical computation especially on the crack growth is still insufficient due to most crack growth studies only being related to surface cracks and not internal cracks [9,10]. The cracks are not only initiated from the surface of a structure, but could also start from the inside thereof [11][12][13]. Thus, it is very crucial to configure the behaviour of the embedded crack since it is not visible to the naked eye.…”

“…For the past two decades, researchers have started to appreciate the use of numerical computations in solving numerous engineering problem [16]. It is commonly used to investigate the power plant [15], in automotives or aircraft [17,18] and for the fatigue life assessment [12,13,[19][20][21][22][23]. Nowadays, there are several commercial software applications that are available in the market for finite element modelling (FEM) [24][25][26].…”

Prediction of fatigue crack growth for semi-elliptical surface cracks using S-version fem under tension loading

“…The FEM is widely used in analysing nuclear power plants [3][4][5], vehicles in automation or aircrafts [6,7] and for fatigue assessment [8][9][10]. However, existing FEM is still insufficient to analyse engineering problems due limitations related to complexity of problems and computation time [11][12][13][14]. Therefore, the S-version FEM was developed to enhance the existing FEM to overcome the constraints mentioned.…”