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Novel monitoring techniques for characterizing frictional interfaces in the laboratory.

Selvadurai PA, Glaser SD - Sensors (Basel) (2015)

Bottom Line: A high definition video camera supplied data for photometric analysis (i.e., the measure of visible light) of asperities along the PMMA-PMMA interface in a direct shear configuration, taking advantage of the transparent nature of the sample material.Normal stress over individual asperities, calculated with the pressure-sensitive film, was compared to the light intensity transmitted through the interface.We found that the luminous intensity transmitted through individual asperities linearly increased 0.05643 ± 0.0012 candelas for an increase of 1 MPa in normal stress between normal stresses ranging from 23 to 33 MPa.

View Article: PubMed Central - PubMed

Affiliation: University of California, Berkeley, CA 94720, USA. pa.selvadurai@berkeley.edu.

ABSTRACT
A pressure-sensitive film was used to characterize the asperity contacts along a polymethyl methacrylate (PMMA) interface in the laboratory. The film has structural health monitoring (SHM) applications for flanges and other precision fittings and train rail condition monitoring. To calibrate the film, simple spherical indentation tests were performed and validated against a finite element model (FEM) to compare normal stress profiles. Experimental measurements of the normal stress profiles were within -7.7% to 6.6% of the numerical calculations between 12 and 50 MPa asperity normal stress. The film also possessed the capability of quantifying surface roughness, an important parameter when examining wear and attrition in SHM applications. A high definition video camera supplied data for photometric analysis (i.e., the measure of visible light) of asperities along the PMMA-PMMA interface in a direct shear configuration, taking advantage of the transparent nature of the sample material. Normal stress over individual asperities, calculated with the pressure-sensitive film, was compared to the light intensity transmitted through the interface. We found that the luminous intensity transmitted through individual asperities linearly increased 0.05643 ± 0.0012 candelas for an increase of 1 MPa in normal stress between normal stresses ranging from 23 to 33 MPa.

No MeSH data available.


Related in: MedlinePlus

(a) An unprocessed image (2136 × 1362 pixels) from the video camera focused on the interface (darker region). Within the dark region are small bright regions that are asperities that transmit light more easily; (b) Test performed to measure the changes in light intensity and its relation to the applied normal force Fn.
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f6-sensors-15-09791: (a) An unprocessed image (2136 × 1362 pixels) from the video camera focused on the interface (darker region). Within the dark region are small bright regions that are asperities that transmit light more easily; (b) Test performed to measure the changes in light intensity and its relation to the applied normal force Fn.

Mentions: As mentioned in Section 2.5, we used a video camera to monitor the light transmitted through contacting asperities in the direct shear experimental configuration. In Figure 6a, we show an unprocessed image taken along the interface. The interface appears darker, and within the darkened section appear small populations of bright asperities. The edges of the image are distorted due to the lens' aperture effect. We focused our analysis on the portion of the image in the red box highlighted in Figure 6a.


Novel monitoring techniques for characterizing frictional interfaces in the laboratory.

Selvadurai PA, Glaser SD - Sensors (Basel) (2015)

(a) An unprocessed image (2136 × 1362 pixels) from the video camera focused on the interface (darker region). Within the dark region are small bright regions that are asperities that transmit light more easily; (b) Test performed to measure the changes in light intensity and its relation to the applied normal force Fn.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481938&req=5

f6-sensors-15-09791: (a) An unprocessed image (2136 × 1362 pixels) from the video camera focused on the interface (darker region). Within the dark region are small bright regions that are asperities that transmit light more easily; (b) Test performed to measure the changes in light intensity and its relation to the applied normal force Fn.
Mentions: As mentioned in Section 2.5, we used a video camera to monitor the light transmitted through contacting asperities in the direct shear experimental configuration. In Figure 6a, we show an unprocessed image taken along the interface. The interface appears darker, and within the darkened section appear small populations of bright asperities. The edges of the image are distorted due to the lens' aperture effect. We focused our analysis on the portion of the image in the red box highlighted in Figure 6a.

Bottom Line: A high definition video camera supplied data for photometric analysis (i.e., the measure of visible light) of asperities along the PMMA-PMMA interface in a direct shear configuration, taking advantage of the transparent nature of the sample material.Normal stress over individual asperities, calculated with the pressure-sensitive film, was compared to the light intensity transmitted through the interface.We found that the luminous intensity transmitted through individual asperities linearly increased 0.05643 ± 0.0012 candelas for an increase of 1 MPa in normal stress between normal stresses ranging from 23 to 33 MPa.

View Article: PubMed Central - PubMed

Affiliation: University of California, Berkeley, CA 94720, USA. pa.selvadurai@berkeley.edu.

ABSTRACT
A pressure-sensitive film was used to characterize the asperity contacts along a polymethyl methacrylate (PMMA) interface in the laboratory. The film has structural health monitoring (SHM) applications for flanges and other precision fittings and train rail condition monitoring. To calibrate the film, simple spherical indentation tests were performed and validated against a finite element model (FEM) to compare normal stress profiles. Experimental measurements of the normal stress profiles were within -7.7% to 6.6% of the numerical calculations between 12 and 50 MPa asperity normal stress. The film also possessed the capability of quantifying surface roughness, an important parameter when examining wear and attrition in SHM applications. A high definition video camera supplied data for photometric analysis (i.e., the measure of visible light) of asperities along the PMMA-PMMA interface in a direct shear configuration, taking advantage of the transparent nature of the sample material. Normal stress over individual asperities, calculated with the pressure-sensitive film, was compared to the light intensity transmitted through the interface. We found that the luminous intensity transmitted through individual asperities linearly increased 0.05643 ± 0.0012 candelas for an increase of 1 MPa in normal stress between normal stresses ranging from 23 to 33 MPa.

No MeSH data available.


Related in: MedlinePlus