Accepted Manuscripts

Marijn Nijenhuis, J. P. Meijaard, Dhanushkodi Mariappan, Just L. Herder, Dannis M. Brouwer and Shorya Awtar
J. Mech. Des   doi: 10.1115/1.4035861
A flexure strip has constraint characteristics, such as stiffness properties and error motions, that govern its performance as a basic constituent of flexure mechanisms. This paper presents a new modeling approach for obtaining insight into the deformation and stiffness characteristics of general three-dimensional flexure strips that exhibit bending, shear and torsion deformation. The approach is based on the use of a discretized version of a finite (i.e. nonlinear) strain spatial beam formulation for extracting analytical expressions that describe deformation and stiffness characteristics of a flexure strip in a parametric format. This particular way of closed-form modeling exploits the inherent finite element assumptions on interpolation and also lends itself for numeric implementation. As a validating case study, a closed-form parametric expression is derived for the lateral support stiffness of a flexure strip and a parallelogram flexure mechanism. This captures a combined torsion-bending-dictated geometrically nonlinear effect that undermines the support bearing stiffness when the mechanism moves in the intended degree of freedom. The analytical result is verified by simulations and experimental measurements.
TOPICS: Bending (Stress), Stiffness, Strips, Deformation, Modeling, Flexure mechanisms, Torsion, Errors, Interpolation, Simulation, Shear (Mechanics), Degrees of freedom, Bearings, Engineering simulation, Finite element analysis
Kosa Goucher-Lambert, Jarrod Moss and Jonathan Cagan
J. Mech. Des   doi: 10.1115/1.4035859
Trying to decide whether to purchase a sustainable product often puts decision makers in a difficult situation, especially if the more sustainable option provides less desirable features or costs a premium. This paper theorizes that adding sustainability as a variable during product choice evaluations create decisions that are moral choice scenarios, where benefit to society is weighed against personal gain. From an engineering design perspective, modeling user preferences in this context can be extremely difficult. While several methods exist to assist researchers in eliciting consumer preferences, the vast majority relies upon conscious input from the potential consumers themselves. More critically, these methods do not afford researchers the ability to understand the cognitive mechanisms underlying what someone may be feeling or thinking while these preference judgments are being made. In this work, functional magnetic resonance imaging (fMRI) is used to investigate the neural processes behind multi-attribute product preference judgments. In particular, this work centers on uncovering unique features of sustainable preference judgments: preference judgments that involve products for which the environmental impact is a known quantity. This work builds upon earlier work that investigated how preference judgments are altered in the context of sustainability. A deeper look at participant decision-making at the time of judgment is examined using neuroimaging with the goal of providing actionable insights for designers and product developers.
TOPICS: Sustainability, Preferences, Magnetic resonance imaging, Decision making, Engineering design, Modeling
Amy Suski
J. Mech. Des   doi: 10.1115/1.4025965
TOPICS: Design

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