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The purpose of this paper is to carry out a set of micromechanical analyses to study the effect of small inclusions on fatigue life of wind turbine bearings.

The local stress concentrations around an inclusion are determined from a characteristic unit cell model containing a single inclusion, using the approximation of a 2D plane strain numerical analysis. The Dang Van multiaxial fatigue criterion is used for the local stresses in the matrix material, to ensure that the stresses remain within the fatigue limit. The matrix material is taken to be one of the most commonly used bearing steels, AISI 52100, and two different types of inclusions are considered. The macroscopic stress histories applied correspond to either a Hertzian or an elastohydrodynamic (EHL) contact pressure distribution under the rollers.

The paper shows that sub-surface fatigue failure due to rolling contact is more likely to develop close to the inclusion-matrix interface, at particular angles that depend on the material and on the inclusion orientation.

Inclusions represent an important issue in the design of wind turbine bearings, that are supposed to work in the very high cycle regime (N>109 cycles). This paper develops a micromechanical study that provides a deeper understanding on effect of inclusions on the fatigue life, according to one of the most used multiaxial fatigue criteria.

To develop the case, the authors used secondary sources including company annual reports, industry reports, news articles, social media sites, academic journal articles and company websites. This case has been classroom tested with students in the MBA Program and Master of Science in Management and Technology Program, and with undergraduates in an operations management course.

Movado Group, which has been a fierce competitor in the luxury watch market, has been facing unprecedented challenges posed by consumers’ enthusiasm for smartwatches and by their love of shopping online. The arrival of the COVID-19 pandemic has intensified these problems and brought new setbacks. This case examines these challenges to the company’s current business model. It then explores opportunities that could transform Movado into an innovative, digitally oriented organization capable of reaching consumers in a dynamic market while combating intense competition from the smart wearable devices that threaten traditional watch companies. The case also discusses the importance of building a robust supply chain through the lens of Industry 4.0 to guard against future supply chain disruptions.

Instructors can use this case in operations and supply chain management classes at the undergraduate and graduate levels. The focus of the case aligns with discussions of supply chain management and Industry 4.0. In particular, the case uses supply chain innovation theory to investigate the implications of Industry 4.0 in the watch industry and dovetails into discussions of omni-channel experience and virtual reality in retail that integrate multiple points of contact to reach consumers efficiently.