6.2: Biaxial Strength of Ultrathin AMLCD Glass Substrates

Gulati, Suresh T.; Helfinstine, J. D.; Roe, T. A.; Hillman, M. L.; Lapp, Josef C.

doi:10.1889/1.1830842

Cited by 8 publications

(8 citation statements)

References 10 publications

(8 reference statements)

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“…Not only are the mean strengths similar, the minimum strength values and Weibull slopes m are nearly identical. These data demonstrate that the strength of asreceived glass is independent of thickness as reported earlier [3], indicating handling and process induced damage is comparable for both thicknesses. The conversion from load to stress was based on finite element analysis (FEA) of this concentric ring test for 1.1 mm and 0.7 mm glasses [5].…”

Section: A) Biaxial Strength Of As-received Glasssupporting

confidence: 86%

See 1 more Smart Citation

62.1: Mechanical Reliability of LCD Panels under Static Loading

Gulati¹,

Helfinstine²,

Bayne³

et al. 2004

Symp Digest of Tech Papers

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Section: A) Biaxial Strength Of As-received Glasssupporting

confidence: 86%

“…A sample size of 30 to 50 specimens, each measuring 50 mm x 50 mm, was used to obtain statistically significant data. The load and support ring diameters were 12.7 mm and 25.4 mm, respectively [3,4]. The loading rate was selected so as to cause failure in approximately 30 seconds.…”

Section: A) Biaxial Strength Of As-received Glassmentioning

confidence: 99%

62.1: Mechanical Reliability of LCD Panels under Static Loading

Gulati¹,

Helfinstine²,

Bayne³

et al. 2004

Symp Digest of Tech Papers

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“…Linear (small deflection) bending of glass in ring on ring (ROR) fixtures is well known and formulated in ASTM standards [1][2][3][4][5]. The standard restricts the deflection to one quarter of the glass thickness.…”

Section: Objectives and Backgroundmentioning

confidence: 99%

63.1: Biaxial Stress in Thin Glass during Ring‐on‐Ring Testing with Large Deflections

Wilcox

Akarapu

Gulati

et al. 2013

Symp Digest of Tech Papers

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Glass substrate strength is commonly evaluated by ring on ring test. Thin substrates may deflect more than 25% of their thickness before fracturing. If so, the standard formulas converting failure load to strength are invalid. We describe a method for converting load to strength, taking into account this large deflectionThe ring on ring test is commonly used in the display industry for evaluating the strength of a monolithic glass substrate. The ASTM standard for this test specifies that the deflection of specimen not exceed 25% of the glass thickness. With current emphasis on light weight panels with glass as thin as 0.3 mm, a specimen may deflect more than 25% of its thickness before fracturing. In such a case, large deflection can result in significant membrane stress. When this occurs, the small deflection formulas of the ASTM standard for converting failure load to strength are no longer valid. This paper provides a more accurate solution for converting failure load to strength, taking account of membrane stress resulting from large deflection. The results presented here show that membrane stress becomes an increasing percentage of the total stress with increasing deflection (and applied load).When large deflection occurs, small deflection (linear bending) theory can overestimate specimen strength significantly. Examples included in this paper illustrate the importance of using large deflection theory to get accurate values of failure stress (strength) for thin glass with the ring on ring test. A key to good measurement is to pay attention to the ratio of deflection to specimen thickness, and use the appropriate method to convert failure load to strength if it exceeds 25% to 50%.

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“…The mechanical integrity of LCD glass substrate has been evaluated previously using both the ring-on-ring test for surface strength and vertical bend test for edge strength [1][2][3][4]. Similarly, the mechanical integrity of LCD panel has been evaluated recently using static and dynamic loading in the center region [ 5,6 ].…”

Section: Theory Of Cylindrical Bendingmentioning

confidence: 99%

59.5: A Novel Test for Evaluating Surface and Edge Strengths of LCD Panel

Helfinstine

Gulati

Roe

et al. 2006

SID Symposium Digest

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The cylindrical bend test offers the unique advantage of stressing both the #1 and #4 surfaces along with their corresponding edges in a uniform manner thereby proofing all of the exposed surfaces to a prescribed stress value dictated by the radius of cylindrical bend fixture. Several LCD panels, comprised of Eagle 2000 and Code 1737 glasses with substrate thicknesses of 1.1 and 0.7 mm and with diagonal dimensions ranging from 5″ to 23″, were tested in the cylindrical bend fixture to stresses ranging from 34 MPa to 83 MPa. Failure modes, fracture origins and strain values on #4 surface and the edges were recorded. The stresses based on cylindrical bend theory were found to be in good agreement with those computed from measured strain components and/or mirror radius. The failure origins were observed both on #4 surface as well as on the edges depending on handling damage and the quality of edge finish. In general, edges appear to be weaker due to their i) inadequate finish and ii) greater vulnerability to handling damage during panel manufacturing.

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6.2: Biaxial Strength of Ultrathin AMLCD Glass Substrates

Cited by 8 publications

References 10 publications

62.1: Mechanical Reliability of LCD Panels under Static Loading

62.1: Mechanical Reliability of LCD Panels under Static Loading

63.1: Biaxial Stress in Thin Glass during Ring‐on‐Ring Testing with Large Deflections

59.5: A Novel Test for Evaluating Surface and Edge Strengths of LCD Panel

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