Barkhausen Demodulation

A careful examination of the magnetization of a ferromagnetic material reveals that it is a discontinuous process; when subject to a varying magnetic field, a ferromagnetic material is magnetized in discrete bursts as domain boundaries overcome pinning at defects in the crystal lattice. This discrete behavior manifests itself as high frequency “noise” superimposed upon a measurement of magnetic flux and is commonly referred to as the Barkhausen Effect. Several important microstructural properties of steel also depend on lattice defect structure, i.e., mechanical hardness, ferrite content, material fatigue, and internal stress state, and investigators have successfully correlated Barkhausen Effect parameters with these properties [1–3]. Unfortunately, Barkhausen noise signals are broadband and weak, characteristics that often limit the utility of the Barkhausen Effect in NDE applications. In this paper, we will describe a phenomenon we call Barkhausen Demodulation, which provides a means of measuring Barkhausen noise that lends itself more readily to NDE investigations. Further, we will describe an experiment in which Barkhausen Demodulation was used to measure the hardness of X40 grade pipeline steel.</p

Barkhausen Demodulation

A careful examination of the magnetization of a ferromagnetic material reveals that it is a discontinuous process; when subject to a varying magnetic field, a ferromagnetic material is magnetized in discrete bursts as domain boundaries overcome pinning at defects in the crystal lattice. This discrete behavior manifests itself as high frequency “noise” superimposed upon a measurement of magnetic flux and is commonly referred to as the Barkhausen Effect. Several important microstructural properties of steel also depend on lattice defect structure, i.e., mechanical hardness, ferrite content, material fatigue, and internal stress state, and investigators have successfully correlated Barkhausen Effect parameters with these properties [1–3]. Unfortunately, Barkhausen noise signals are broadband and weak, characteristics that often limit the utility of the Barkhausen Effect in NDE applications. In this paper, we will describe a phenomenon we call Barkhausen Demodulation, which provides a means of measuring Barkhausen noise that lends itself more readily to NDE investigations. Further, we will describe an experiment in which Barkhausen Demodulation was used to measure the hardness of X40 grade pipeline steel.</p

Forming a Community of Practice to Support Faculty in Implementing Course-Based Undergraduate Research Experiences

There is an urgent need to influence educational change in the methods by which science is taught. Numerous national agencies have called for science, technology, engineering, and mathematics (STEM) educational reform with recommendations to address retention and increase diversity of students in STEM disciplines. One way to address these recommendations is by replacing the widespread traditional approach to foundational laboratory courses with course-based undergraduate research experiences (CUREs). As a creative alternative to one-on-one research mentorships, CUREs scale up the research experience to reach a greater number of students, many of whom would otherwise not be able to participate in research. Increasing the adoption of CUREs in foundational chemistry laboratory courses exposes a larger, more diverse population of STEM students to research experiences. The greatest impact of these experiences occurs in populations that are traditionally underrepresented in STEM disciplines, whose college experiences are enhanced by being a part of a diverse community. A Community of Practice brings together people with a common interest or goal. This chapter describes our steps to form a Community of Practice comprised of faculty from Primarily Undergraduate Institutions, community colleges, and high schools with the goal of providing a supportive framework that lowers barriers to CURE development and implementation for faculty in foundational chemistry laboratories