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Abstract BackgroundSuperelastic shape memory alloys (SMAs) such as nickel-titanium, also known as Nitinol, recover large deformations via a reversible, stress-induced martensitic transformation. ObjectivePartitioning the deformation into the contributions from superelasticity and plasticity and quantifying the interaction between these mechanisms is key to modeling their fatigue behavior. MethodsWe capture these microscopic interactions across many grains using a combination of scanning electron microscopy digital image correlation (SEM-DIC) and electron backscatter diffraction (EBSD). Modeling our data as a statistical distribution, we employ a Gaussian Mixture Model (GMM) soft clustering framework to understand how these mechanisms interact and evolve as a function of global strain. ResultsOur findings show that, under globally-applied uniaxial tensile loading, plasticity bridges deformation in regions where competing positive and negative martensitic shear bands intersect. Early stage transformation-induced plasticity is concentrated at these intersections and forms concurrently with the Lüders-like martensitic transformation front, often appearing with a zig-zag pattern that is linked to compound twinning at the martensite-martensite interface. At higher strains, austenite slip is activated as a second mechanism of plastic deformation. ConclusionsWe propose that this plastic bridging mechanism underpins the prestrain effects previously reported in the literature, where higher prestrains can enhance the fatigue strength of superelastic materials within a given loading mode. 

A strong understanding of technical knowledge is necessary for all engineers, but understanding the context in which engineering work takes place is just as important. Engineering work impacts people, communities, and environments, and there is increasing recognition of the importance of preparing engineers to account for these sociocultural dimensions. The engineering curriculum needs to include both technical and sociocultural topics to prepare students as holistically competent engineers. A call for broader engineering skills is evident in ABET student outcomes, a few of which directly denote the importance of students’ ability to identify the ethical, cultural, and social impact engineers have on society. However, engineering education continues to underemphasize or omit entirely non-technical aspects of engineering practice. Technical knowledge persists as the central focus in engineering classes. Omitting sociocultural material in engineering classes can result in the development of future engineers whose designs further perpetuate social and systemic inequities, such as environmental pollution that affects vulnerable populations or inefficient designs that risk human lives. Additionally, emphasizing sociotechnical content in undergraduate engineering courses can help attract and retain a more diverse population of students who value socially relevant engineering work. A deep grounding in both technical and social skills and knowledge is particularly important in Industrial Engineering (IE), a field that focuses on analyzing data to improve systems and processes and which tends to focus more on human and business dimensions than many other engineering fields. Even so, there is little evidence to indicate that sociocultural skills and knowledge are taught in IE courses. Because the curricular focus of a field communicates to students what is and is not valued in the field, students who enter IE with a strong desire to advance social good may learn that such a goal is inconsistent with the field’s values and ultimately feel alienated or disinterested if social dimensions are not incorporated into their coursework. More insight is needed into the kinds of messages IE coursework sends about the nature of work in the field and the opportunities these courses provide for students to develop the sociotechnical knowledge and skills that are increasingly crucial in Industrial Engineering. In an effort to characterize how, if at all, core courses in IE facilitate students’ development of sociotechnical engineering skills, this research paper examines the general content of core IE courses at a predominantly white institution. This paper draws on data generated for a larger research study that leverages Holland et al.’s Figured Worlds framework to explore the messaging undergraduate engineering students receive in their classes around valued knowledge in their field. In this study, we draw on observation data leveraging recordings of seven required undergraduate courses in IE. We analyzed three randomly selected sessions from each course, with a total of 21 unique sessions observed. Our findings describe the practices that are and are not emphasized within and across required IE courses and the ways these practices are discussed. Our characterization of emphasized engineering practices provides an important foundation for understanding what is communicated to students about the nature of engineering work in their field, messaging which has substantial implications for the population of students who enter and persist in the field beyond their undergraduate studies. 

The success of a design is not determined solely by its technical aspects. A design must work for the people who will be using it and in the context in which it will be used. Human-centered design approaches suggest strategies to remind engineering designers of the people impacted by their design decisions. While many of these strategies can be used within and across multiple design phases, during the act of sketching concepts during concept generation, there are few explicit strategies for centering people. We investigate possible impact from a simple intervention during a concept generation task through a between-subjects experiment. Working alone is a single design session, half of a group of mechanical engineering students were asked to explicitly “represent people” within their conceptual sketches. Afterwards, all students reviewed each of their concepts to answer, “Who is this idea for? Who do you imagine would use it?” Those who received the intervention requiring representation of people within concept sketches produced significantly longer reflections with greater depth compared to the control group. Adding drawings of people to sketches resulted in more consideration of the social and physical context of use and of the user's personal preferences and values. Depicting people in generated concepts substantially reduced claims a design is "for everyone,” suggesting explicit representation of potential users produced more thoughtful consideration of diversity among potential users.