Fracture assessment of magnetostrictive materials

Abstract

Giant magnetostrictive materials are gaining interest in the field of smart material, especially the commercially known Terfenol-D, that is an alloy made out of iron, terbium and dysprosium (Tb 0.3 Dy 0.7 Fe 1.9). Since these smart materials are subjected to both mechanical loads and magnetic field during their industrial applications, an extensive characterization on the influence of a magnetic field and of defects on their fracture behavior is needed. Very few works can be found in literature about this topic and, thus, the purpose of this work is to partially fill this lack by means of three-point bending tests on single-edge pre-cracked Terfenol-D specimens. Failure loads have been measured at different loading rates and under magnetic fields of various intensities. Since giant magnetostrictive materials are very brittle, the strain energy density (SED) approach has been exploited by means of couplefield finite element analyses. SED has revealed itself as a robust parameters in the assessment of the magnetic field and loading rate effects on fracture resistance, allowing also to propose a relationship between the radius of the control volume and the loading-rate.

Fracture Assessment of PEEK under Static Loading by Means of the Local Strain Energy Density

“…Yet PEEK is available in different grades and formats depending on the application and processing method. The question remains, if the presented approach still holds for different PEEK grades and geometries, especially when the critical SED value cannot be analytically obtained but the fracture toughness is known [ 31 , 32 , 33 ]. This will be the topic of the next section.…”

Fatigue Strength Assessment of Steel Rollers: On the Reliability of the Strain Energy Density Approach on Real Components

“…[23] has been used. The approach has then been successfully applied to either the tensile or fatigue assessment of several notched materials, from metals [24][25][26][27][28][29][30][31][32] to polymers [33][34][35] and ceramics [36,37].…”

Fracture behaviour of notched as-built EBM parts: Characterization and interplay between defects and notch strengthening behaviour

“…Despite these significant advances in understanding the impact of processing conditions on the mechanical behaviour of parts, the effect of geometric discontinuities such as notches is so far underexplored. Yet, this is highly relevant in the field of complex geometric design as such attempts naturally introduce such discontinuities reported to strongly affect both tensile and fatigue properties of the components [16][17][18][19][20][21][22][23][24][25][26]. In fatigue, the effect of notches is unambiguous, determining a reduction in the fatigue strength for several materials [27][28][29][30][31][32][33][34].…”