Developing “Design by Analysis” Methods for Glassy Polymers for Pressure Vessels
Commercial diving systems, medical hyperbaric systems, and submersibles were the driving applications for the development of using glassy polymers such as poly methyl methacrylate (PMMA), also known as acrylic, and polycarbonate (PC) materials for pressure vessels for human occupancy (PVHO). PVHOs have heightened safety concerns beyond conventional pressure vessel hazards because a rapid decompression may not damage the pressure vessel but can kill the occupants. PVHOs require windows in order to observe the occupants and assess their health or to allow the occupants to look outwards to operate equipment. The current methods for designing acrylic structures are constrained to specific shapes, are empirically based, do not calculate stresses or deflections, and are essentially unchanged since the 1970s. Conversely, the methods for designing pressure vessels using metallic or nonmetallic materials has advanced considerably, to include methods for design and in-service evaluations using modern methods such as Finite Element Analysis. The current PVHO methods have been proven to be reliable but are constrained to the limited range of shapes and conditions tested over 45 years ago. This limits the ability to innovate the use of PMMA and PC. This has become more critical with the pending adoptions of acrylic material in conventional pressure vessel applications in Section VIII of the Boiler and Pressure Vessel Code. While conventional pressure vessels have range of material definitions, the PVHO code has a minimum material properties that do not reflect the range of PMMA and PC that could be used. Conventional pressure vessel calculations incorporate material properties into their calculations, whereas the PVHO code uses empirical design tables. New methods are needed to incorporate classic design principles into using glassy polymers into pressure vessel designs beyond the parameters of the ASME PVHO code. Given the strength of the glassy polymers are more than an order of magnitude less than the metallic portions, the thickness of the polymer sections generally exceeds the thin wall “membrane” theory used in Section VIII, Divisions 1 and 2. This creates multiple challenge in developing new methods which have the same safety and reliability of current methods. This poster summarizes the approach presented in “Developing ‘Design By Analysis’ methodology for PVHOs using V&V and Stochastic FEA” to be published in ASCE/ASME Journal of Risk and Uncertainty in Engineering Systems, Part B: Mechanical Engineering in September, 2020 and presents how the risk and uncertainty of the new methodology is mitigated through Verification and Validation (V&V). The design methodology has potential applications beyond pressure vessels including aerospace and architectural uses.
Developing “Design by Analysis” Methods for Glassy Polymers for Pressure Vessels
Category
Poster Presentation
Description
Session: 17-01-01 Research Posters - On Demand
ASME Paper Number: IMECE2020-25369
Session Start Time: ,
Presenting Author: Bart Kemper
Presenting Author Bio: Bart Kemper, P.E. is the principal engineer of Kemper Engineering Services. He has worked in the marine, subsea, commercial diving, petrochemical, biomedical, forensic, and defense industries. Kemper is also a retired US Army engineer officer whose work has spanned five continents. Kemper is a member of the ASME Codes & Standards for Pressure Vessels for Human Occupancy (PVHO) and is Chair of the PVHO Viewports Subcommittee as well as part of the Emerging Technologies Task Force for the National Society of Professional Engineers. He has published over 30 professional papers and patents in area ranging from biomedical devices to infrastructure assessment to green energy production. He is chair for the “Design By Analysis” task group for ASME PVHO.
Authors: Bart Kemper Kemper Engineering Services, LLC
Linda Cross Kemper Engineering Services