John D. Helfinstine

Hardness, elastic modulus, and fracture toughness bulk properties in Corning calcium fluoride

Knoop and Vickers hardness, Youngs Modulus, and fracture toughness measurements were performed on Cornings Code 9575 calcium fluoride in various orientations. Other commercially available sources of calcium fluoride were also measured for comparison of properties. Knoop hardness and elastic properties exhibited a dependence on orientation while no such dependence was observed for Vickers hardness and fracture toughness. The results also indicated that these physical properties were not dependent on the source of the material

Measuring the inert strength of large flaws in optical fiber

A ratio of inert to ambient strength >= 1.5 is suggested for large flaws in optical fiber near the proof stress level. Also, a temperature dependent strength at low temperatures, similar to that observed in pristine fibers, was investigated. An increase in fracture toughness or changes to the crack tip geometry at low temperatures did not account for the increase in strength at low temperatures. Inert strength distributions were predicted from strength obtained under ambient conditions for as-manufactured fiber and fibers with handling damage.

HIGH TEMPERATURE FATIGUE IN CERAMIC WALL-FLOW DIESEL FILTERS

Under certain operating conditions when the combined stresses in a ceramic wall-flow diesel filter from mechanical, thermal, and vibrational loads exceed its threshold strength, the fatigue effects become important. This paper reviews the theory of static and dynamic fatigue, and presents fatigue data for Cornings high efficiency filter composition (EX-47, 100/17) in the temperature range 25/sup 0/ - 400/sup 0/C which is representative of the stressed peripheral region during regeneration. The measurement and analysis of fatigue data, together with the implication on long-term durability of cordierite ceramic filters, is discussed.

6.2: Biaxial Strength of Ultrathin AMLCD Glass Substrates

The biaxial strength of ultrathin AMLCD glass substrates with thickness ranging from 0.25mm to 0.70mm was measured in the concentric ring fixture. The data, based on a large sample size of 25mm × 25mm square specimens, show that the strength is independent of glass thickness and approaches 630 MPa. The choice of 25mm × 25mm specimens for measuring the biaxial strength was dictated by minimizing large deflections and associated membrane tension in the test region. The effect of surface area under test was taken into account by using Weibull distribution which demonstrated constancy of surface strength irrespective of substrate thickness. Thus, thin and ultrathin AMLCD susbtrates have similar biaxial strength as measured in the concentric ring fixture.

69.4: Superior Cuttability Performance of Jade™ Glass for Thin and Strong Mobile Displays

In addition to thermal stability of Cornings Jade™ glass, its cuttability is better suited for mobile displays with thin panels. The key focus of this paper is to provide cuttability data for thin Jade glass substrates. These data confirm that Jade offers easier panel separation than that for a-Si glasses without compromising panel strength.

48.1: Behavior of LCD Panel During Bending

When an LCD panel is subjected to pure bending, for example during strength measurement or proof testing, the question arises “does it behave as a monolith of twice the substrate thickness? or does it behave as two independent substrates?”. Both theory and experiment suggest that the panel behavior depends on how its edges are held together, i.e. well bonded? or loosely held together? Indeed, the former renders the panel nearly twice as strong and four fold as stiff as the latter. This paper will provide the analysis of the bending behavior of a two-layer laminate using St Venant flexure theory. Experimental data, using strain gages, will demonstrate that an LCD panel can behave either as a monolith of twice the substrate thickness or two independent substrates depending on how its four edges are held together in the support structure including the bezel. The paper derives appropriate equations for computing panel strength when it is bent to constant curvature or when its specimens are flexed in 4-point bending for both i) well bonded edges and ii) loosely held edges.

44.3: Mechanical Robustness of Thin AMLCD Glass Substrates Under Point Loading

The biaxial strength of 0.7mm thick AMLCD substrates of Code 1737G glass was measured under the point loading using hemispherical lifter pin made from two different materials, namely PEEK plastic and aluminum metal. The effect of impact-generated damage by these pins on biaxial strength was also quantified using strain gages on tension and compression sides. The data show that biaxial strength under point loading is 34% higher that due to a uniform bending moment over a large central area. The effect of impact damage of up to 4.5N** force was quantified using this test. The minimum strength of as-received specimens was reduced by 14% in the case of PEEK lifter pin and 41% in the case of aluminum pin suggesting the latter to be more damaging that PEEK lifter pin. The mean strength, however, was not affected adversely.

6.5: Mechanical Integrity of an AMLCD Panel

This paper examines the mechanical strength of both the surfaces and edges of AM LCD panels made from Code 1737 and Eagle2000™ boroaluminosilicate glasses. Depending on handling, finishing and processing conditions employed by the panel manufacturer, our data show that edge strength can be lower or higher than the surface strength. This is particularly true of #4 surface.

47.4: Effect of Glass Thickness on Stress in a Centrally Loaded LCD‐TV Panel

An analytical solution, based on linear plate theory, shows that the maximum tensile stress in an LCD-TV panel loaded at the center and simply supported at the four edges depends on several independent factors, namely i) glass thickness, ii) nature of the load, whether static or dynamic, iii) constraints on the center deflection, and iv) details of the cell structure, such as the size, spatial density and properties of the cell spacers and their response to the load. In the case of static load, a thicker panel will experience higher stresses than a thinner panel for identical values of center deflection. In the case of dynamic load, i.e. impact by a spherical ball, the thicker panel will also experience higher stresses than a thinner panel for identical values of center deflection. Experimental data based on strain gages and fractographic analysis of fracture origins are in progress to examine the pros and cons of thick vs. thin glass panels from a mechanical durability point of view. Dynamic loading can induce higher stresses than static loading and hence is a more sever test for mechanical durability.

6.2: Mechanical Properties of Jade™ Glass Substrate for LTPS Application

Mechanical properties of Jade™ glass substrate, including ring-on-ring strength of surfaces, vertical bend strength of ground edges, dynamic fatigue constant, fracture toughness, and Youngs modulus, are presented. This high strain point glass is designed to meet low compaction requirement for low temperature polysilicon process (LTPS). Its fusion surface quality ensures pristine surfaces with high strength. Its superior edge finish leads to high edge strength. Its composition and manufacturing process eliminate the need for post-forming thermal treatment. Its intrinsic thermal stability minimizes viscous distortion during LTPS processing. Its fracture toughness is similar to that of a-Si glasses, yet its fatigue resistance is superior due, primarily, to its composition.