1,720,960 research outputs found
Fatigue behaviour of thin Fe-Si steel sheets for electric motor production
Full text linkThe on-going evolution toward electric/hybrid traction requires the development of
high-performance electric motors. The rotor of electric motors is made from a stack of thin steel
sheets and a complex configuration of magnets. Electric steels are typically Fe-Si alloys where
Si addition controls grain size. Mechanical durability assessment of electric motors is based on
the fatigue performance of Fe-Si steels.
This contribution reports a thorough mechanical characterisation of a Fe-Si alloy in the form of
thin (i.e. 0.2 mm) sheets. Numerous tensile tests were performed to characterize the reference
static properties and their respective scatter. A suitable fatigue testing procedure for thin sheets
was developed and used in an extensive campaign aimed at investigating the directional fatigue
behaviour of the Fe-Si steel. Comparison with literature data confirms that the fatigue response
of thin sheets is affected by different factors related especially to the method of extraction
Design and Development of Patient-Specific Medical Devices for Maxillofacial Surgery Through 3D Modeling, Topology Optimization, and Additive Manufacturing
No full textAdditive manufacturing presents unique opportunities for developing patient-specific medical devices and tools in orthognathic surgery. Devices used in maxillofacial surgery present several constraints which refer to the specific characteristics of the patient and the stress conditions that are in place during the surgery. This paper describes an integrated workflow used for the identification, design, optimization, and production of patient-specific devices while promoting synergy among specialists of vastly different backgrounds. Medical specialist interprets Computed Tomography scans with three-dimensional reconstruction of the patient and, supported by a CAD specialist design the required tools to restore the patient functionality. Preliminary tooling designs are checked for strength and stiffness by a structural engineer considering the mechanical properties of the perspective AM materials and passed in digital form to the AM technologist who will be responsible of the 3D printing. The medical specialist uses the devices through physical prototypes to assess effectiveness and usability. The integrated workflow allows to increase accuracy while reducing surgical time and costs
Influence of random fatigue loading non-proportionality on damage
No full textThe aim of the present paper is to evaluate the effect of the loading non-proportionality on damage accumulation. Such an analysis is performed at material macro-level by means of numerical simulations concerning random bending-torsion loading. A wide group of random bending and torsion input signals is generated by varying (a) the spectral content and variance of the above signals, and (b) the value of the cross correlation coefficient. The spectral criterion by Carpinteri et al. is applied to compute the expected damage. A linear relationship between damage ratio and cross correlation coefficient is proposed for signals characterised by variance ratio equal to 1.0
Fatigue assessment of notched specimens by means of a critical plane-based criterion and energy concepts
No full textA strain-based multiaxial fatigue criterion previously proposed for fatigue assessment of unnotched specimens is here extended to the case of notched ones. Such a criterion is a reformulation of the stress-based multiaxial High-Cycle Fatigue (HCF) criterion by Carpinteri and Spagnoli. The extension herein presented considers as the critical point, where to perform the fatigue assessment, the material point located at a certain distance from the notch tip, depending such a distance on both the biaxiality ratio (defined as the ratio between the applied shear stress amplitude and the normal stress amplitude) and the control volume radii R1 (related to Mode I) and R3 (related to Mode III). Some multiaxial fatigue data related to specimens made of titanium grade 5 alloy (Ti–6Al–4V) and weakened by sharp notches are examined to validate the extended criterion. © 2016 Elsevier Lt
Modified two-parameter fracture model for bone
No full textThe analysis of the bone fracture behaviour is fundamental for prevention, diagnosis and treatment of traumas. In the present paper, an experimental campaign on fracture behaviour of bovine femoral cortical bones is conducted to characterise the fracture toughness, KICS, which is related to the structure and load-bearing capacity of bones. Firstly, KICS is evaluated through a two-parameter model originally proposed for quasi-brittle materials. To take into account the crack deflection (kinked crack) due to osteons orientation, the two-parameter model is modified by applying the Castigliano theorem. Fracture toughness results here obtained are compared with those related to a femur of an 18-month-old bovine, available in the literature
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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