Keynote speakers

Mr. Vilhelm Söderberg

Industrial Ph.D student, AB Volvo and KTH

Heavy duty trucks in 2045

Presentation abstract: The transport sector is rapidly changing, driven by a common understanding that the environmental footprint from transportation needs to be reduced. Road transports are today dominated by internal combustion engines burning fossil fuel. But how will the powertrain in a heavy duty truck look like in 2045? The presentation will paint a scenario based on interviews with experts from the industry and findings from academia.

Biography

Vilhelm has a master’s degree in engineering physics from Uppsala Universitet. After graduation he stayed at Uppsala Universitet working as a research engineer at the division for Solid state Physics. In 2007 Vilhelm left academia and started his career in the industry. He has worked for both SMEs and large global companies, but all the time close to production. In 2021 Vilhelm took the next step and started his PhD studies at KTH as an Industrial PhD student.

Professor Stefan Jonsson

Professor in Materials Science at KTH, Royal Institute of Technology, Stockholm

The Barkhausen Noise Technique, principles and applications

Presentation abstract: Magnetism and the principle of the Barkhausen Noise Technique will be discussed in relation to microstructures and stresses. Applications will be taken from specific tests, calibration tests and inline screening of hardened and ground cam- and crankshafts at Scania, Södertälje. The intention is to give an overview of the subject, increase the understanding of the technique and to present interesting application measurements.

Biography

Professor Jonsson received his PhD in thermodynamics 1993, using the Calphad technique and Thermo-Calc program to model the Si-Al-O-N and Ti-W-C-N systems. During the following five years he worked at Swedish Institute for Metals Research (now Swerim) as leader for the heat treatment group, also responsible for residual stress measurements using XRD. In 1999 he returned to KTH and soon became responsible for Mechanical Metallurgy becoming full professor in 2006.

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In 2008 a mobility grant from SSF, Swedish Foundation for Strategic research, initiated a prosperous collaboration with the truck manufacturer Scania CV AB in Södertälje. The research has focused on Barkhausen Noise measurements on camshafts and crankshafts; corrosion, creep and fatigue of exhaust manifolds; hardening distortions of power-train gears and cavitation erosion in materials for cylinder liners. Professor Jonsson is also working in medical technology, being one of the inventors of the “Extroducer”, recently approved by FDA for human use, where hard-to-reach organs can be accessed by catheters following the vasculature.

Mr. Samuli Savolainen

Stresstech, Product Manager

Automating Barkhausen noise measurement

Presentation abstract: In the last four decades of Barkhausen noise analysis, industry demands have increased dramatically. Parts to be analyzed are more complex, variation between different parts is greater and quality analysis cycle time is minimized. To answer all these demands Stresstech has developed robotized and automated systems for Barkhausen noise analysis.

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With well-designed Barkhausen noise system, measurement repeatability, measurement speed and sensor lifetime can achieve maximum level and electromagnetic interference can be minimized. Sensor and sensor fixture designs are in key role when automation level of the system increases. User interfaces plays a big role in the industry systems. It is important to design systems that are easy to use and ergonomic.

In this presentation the current industry demands along with the state-of-the-art solutions in industrial level Barkhausen noise measurement quality inspection is covered.

Biography

Samuli Savolainen is a product manager at Stresstech. In his role he turns knowledge from science to products that many different industries need. He has a wide knowledge from very simple manual products to fully automated inline solutions in field of residual stress measurement, heat treatment verification and grinding burn detection. Samuli has worked with Barkhausen noise analysis almost two decades.

Dr. Lasse Laurson

Professor of Computational Physics, Tampere University, Finland

Modelling Barkhausen noise – a statistical physicist’s perspective

Presentation abstract: Barkhausen noise in ferromagnets is an example of a rather broad class of systems exhibiting what is often labeled as “crackling noise” by statistical physicists. Systems displaying crackling noise respond to a slowly changing external driving field by exhibiting a sequence of avalanches with a broad, scale-free size distribution. In addition to Barkhausen noise, other notable examples in materials physics include the plastic deformation process of micron-scale crystalline solids,

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as well as the bursty propagation of cracks in disordered solids, but similar phenomena can be observed in a wide range of contexts beyond the traditional realm of physics, ranging from neuronal avalanches in the brain to volatility clustering in financial markets.

I will start by presenting an overview of Barkhausen noise from the perspective of a statistical physicist. Typically, one starts from the rather well-established assumption that the noise originates from the jerky field-driven motion of domain walls interacting with various impurities and imperfections in the magnet, something that is often modelled by considering domain walls as driven elastic interfaces in random media. This then leads one to study the depinning transition of domain walls, and how the statistical properties of Barkhausen noise reflect the universality class of the transition, governed by things like the range of interactions and the spatial dimensionality of the system.

Then, I will briefly discuss our recent modelling efforts focusing especially on the problem of Barkhausen noise in thin film geometry. First, I will discuss modelling Barkhausen noise in thin films with uniaxial in-plane anisotropy, where the competition between the domain-wall surface tension and dipolar interactions induces a crossover between a rough domain-wall phase at short length scales and a large-scale phase where the walls display a zigzag morphology [1]. The two phases are characterized by different critical exponents for Barkhausen avalanche dynamics that are in quantitative agreement with experimental measurements on MnAs thin films. Finally, I discuss modelling of Barkhausen noise in disordered Pt/Co/Pt thin films with PMA due to precessional motion of domain walls using full micromagnetic simulations, allowing for a detailed description of the domain wall internal structure [2]. In this regime the domain walls contain topological defects known as Bloch lines which repeatedly nucleate, propagate, and annihilate within the domain wall during the Barkhausen jumps. In addition to bursts of domain wall propagation, the in-plane Bloch line dynamics within the domain wall exhibits crackling noise and constitutes the majority of the overall spin rotation activity.

[1] L. Laurson, G. Durin, and S. Zapperi, Universality classes and crossover scaling of Barkhausen noise in thin films, Phys. Rev. B 89, 104402 (2014).
[2] T. Herranen and L. Laurson, Barkhausen noise from precessional domain wall motion, Phys. Rev. Lett. 122, 117205 (2019).

Biography

Lasse Laurson got his PhD in physics from Helsinki University of Technology in 2008 in the group of Prof. Mikko Alava, after which he moved to Turin, Italy for a postdoctoral position at the ISI Foundation in the group of Prof. Stefano Zapperi. Thanks to a postdoctoral grant from the Academy of Finland, Laurson returned to Aalto University, Finland in 2011, and subsequently worked there as an Academy Research Fellow. In 2018, Laurson started as an Associate Professor at Tampere University, Finland. Since 2021 he works there as a full professor of computational physics. His research focuses on “complexity in materials”, especially avalanche dynamics in driven systems, including, e.g., strain bursts in plastically deforming crystals, fluctuations in crack propagation in disordered solids, as well as the Barkhausen effect in disordered ferromagnets.