Christopher Brown

Prof. Christopher Brown

Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA
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Research Focus & Metrics

Academic Career Length

27Years (2000-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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3 June 2014 in The International Journal of Advanced Manufacturing Technology
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Journal Article
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SLSylvain Lavernhe
Sylvain Lavernhe
YQYann Quinsat
Yann Quinsat
CLClaire Lartigue
Claire Lartigue
Christopher BrownChristopher Brown
Christopher Brown


7 July 2020 in Materials
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Journal Article
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Tomasz BartkowiakTomasz Bartkowiak
Tomasz Bartkowiak
JBJohan Berglund
Johan Berglund
Christopher BrownChristopher Brown
Christopher Brown
Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a µEDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.

18 December 2017 in Journal of Manufacturing Science and Engineering
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Tomasz BartkowiakTomasz Bartkowiak
Tomasz Bartkowiak
Christopher BrownChristopher Brown
Christopher Brown
The objectives of this work are to demonstrate the use of multiscale curvature tensor analysis for characterizing surfaces of stainless steel created by micro-electrical discharge machining (μEDM), and to study the strengths of the correlations between discharge energies and resulting surface curvatures (i.e., principal, Gaussian, or mean curvatures) and how they change with scale. Surfaces were created by μEDM techniques using energies from 18 nJ to 16,500 nJ and measured by confocal microscope. The curvature tensor T is calculated using three proximate unit vectors normal to the surface. The multiscale effect is achieved by changing the size of the sampling interval for the estimation of the normals. Normals are estimated from regular meshes by applying a covariance matrix method. Strong correlations (R2 > 0.9) are observed between calculated principal maximal and minimal as well as mean and Gaussian curvatures and discharge energies. This method allows detailed analysis of the nature of surface topographies and suggests that different formation processes governed the creation of surfaces created by higher energies.

3 January 2020
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Book Chapter
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Erwin RauchErwin Rauch
Erwin Rauch
AVAndrew R. Vickery
Andrew R. Vickery
Christopher BrownChristopher Brown
Christopher Brown
Dominik T. MattDominik T. Matt
Dominik T. Matt
SME manufacturers face the challenge of implementing smart and highly adaptable manufacturing systems to produce individual products at the lowest price and with the shortest lead time. This chapter shows an approach based on an explorative field study combined with Axiomatic Design theory to collect the specific requirements of SMEs introducing Industry 4.0 in their production. Customer/user needs for the design of smart and adaptable SME manufacturing systems are transferred into functional requirements. These functional requirements are then used to define a set of design parameters and guidelines, which are addressed to support practitioners from industry in the implementation of smart manufacturing systems. These guidelines help system designers to improve their design at an early stage before making costly decisions and to reduce complexity to a minimum.

14 January 2019 in Materials
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Journal Article
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Tomasz BartkowiakTomasz Bartkowiak
Tomasz Bartkowiak
Christopher BrownChristopher Brown
Christopher Brown
The objectives of this paper are to demonstrate the viability, and to validate, in part, a multiscale method for calculating curvature tensors on measured surface topographies with two different methods of specifying the scale. The curvature tensors are calculated as functions of scale, i.e., size, and position from a regular, orthogonal array of measured heights. Multiscale characterization of curvature is important because, like slope and area, it changes with the scale of observation, or calculation, on irregular surfaces. Curvatures can be indicative of the topographically dependent behavior of a surface and, in turn, curvatures are influenced by the processing and use of the surface. Curvatures of surface topographies have not been well- characterized yet. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. Manufactured surfaces are studied for further validation of the calculation method because they provide certain expectations for curvatures, which depend on scale and the degree of curvature. To study a range of curvatures on manufactured surfaces, square edges are machined and honed, then rounded progressively by mass finishing; additionally, a set of surfaces was made by turning with different feeds. Topographic measurements are made with a scanning laser confocal microscope. The calculations use vectors, normal to the measured surface, which are calculated first, then the eigenvalue problem is solved for the curvature tensor. Plots of principal curvatures as a function of position and scale are presented. Statistical analyses show expected interactions between curvature and these manufacturing processes.