Strength of glass from Hertzian line contact
- Cai, W.; Parks, R. E.; et. al.
In optical lens assembly, metal retaining rings are often used to hold the lens in place. If we mount a lens to a sharp metal edge using normal retention force, high compressive stress is loaded to the interface and the calculated tensile stress near the contact area from Hertzian contact appears higher than allowable. Therefore, conservative designs are used to ensure that glass will not fracture during assembly and operation. We demonstrate glass survival with very high levels of stress. This paper analyzes the high contact stress between glass lenses and metal mounts using finite element model and to predict its effect on the glass strength with experimental data. We show that even though contact damage may occur under high surface tensile stress, the stress region is shallow compared to the existing flaw depth. So that glass strength will not be degraded and the component can survive subsequent applied stresses.
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