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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records

A parametric finite element study for determining burst strength of thin and thick-walled pressure vessels

To accurately predict the burst strength of both thin and thick-walled pressure vessels (PVs), a parametric study of PV burst strength was performed for a wide range of vessel geometries and materials using elastic-plastic finite element analysis (FEA). A valid FEA model was established through a detailed study of 2D versus 3D FEA models, the critical stress failure criterion versus the limit load criteria, and the thick-wall effect on the FEA simulations. Here, the results show that the stresses and strains at the mean diameter, rather than outside diameter, determines a more accurate burst strength for both thin and thick-walled PVs. On this basis, a parametrized FEA script using the ABAQUS Python application programming interface (API) was used to create a large database of PV burst strengths for a variety of vessel geometries and materials, demonstrating that Python scripting is a powerful technique for performing parametric studies or generating large databases. From the FEA results, using the regression method, a new burst pressure model was developed as a function of the vessel geometry (D/t ratio) and material properties (UTS and n). As validated by a large number of full-scale burst test data, the proposed burst model can very accurately predict the burst strength for both thin and thick-walled PVs.

42 ENGINEERING↗

EXPERIMENTAL VALIDATION OF THEORETICAL BURST STRENGTH SOLUTION FOR DEFECT-FREE THICK-WALLED PIPES

The burst pressure of line pipes is an important strength property required in pipeline design and integrity management. Historically, the Barlow formula in conjunction with the ultimate tensile stress (UTS) of pipeline steels were utilized to estimate the burst strength of line pipes. However, the Barlow formula did not consider the plastic flow effect for ductile steels and is applicable only to thin-walled pipes. In 2006, the present author proposed a new multiaxial plastic yield theory and obtained a theoretical Zhu-Leis solution of burst strength for defect-free thin-walled pipes in term of UTS and strain hardening exponent n of pipeline steels. The Zhu-Leis solution has been validated by various burst test data for thin-walled pipelines for a wide range of steel grades from Grade B to X120. Recently, the present author extended the Zhu-Leis theory of plasticity to thick-walled pipes and obtained the Zhu-Leis solution of burst pressure for thick-walled pipes. The proposed burst pressure solution is applicable to both thin and thick-walled pipes. To experimentally validate the proposed theoretical burst pressure solution, this paper obtains a set of burst test data for three thick-walled pipes in Grade B carbon steel with a nominal diameter of 2.375 inches and three nominal wall thicknesses, resulting in D/t = 15.4, 10.9, 6.9. Through comparisons, these burst data validate the theoretical burst pressure solution for thick-walled pipes. Moreover, two additional burst test datasets collected from literature for thin and thick-walled pipes further validate the proposed burst pressure solution for both thin and thick-walled pipes.

Zhu, Xiankui↗

Static and dynamic fatigue behavior of glass filament-wound pressure vessels at ambient and cryogenic temperatures.

Investigation of the pressure load carrying capacity and fatigue strength of filament-wound glass-reinforced plastic pressure vessels subjected to static and cyclic loading at ambient and cryogenic (liquid nitrogen) temperature environments. The results indicate that the static fatigue problem is not critical at cryogenic temperatures. Under static loading at liquid nitrogen temperature, a reinforced plastic cylinder sustained pressurization for 88 days without failure at about 90% of the single cycle burst strength. At ambient temperature, the static life at 90% of the burst strength was about 7 min. Under cyclic loading in liquid nitrogen, no failure resulted after 1509 cycles at 55% of the single cycle burst strength. Under the same cyclic loading at ambient temperature, the test results would predict failure in the reinforced plastic. The results of similar tests upon adhesively bonded polyimide aluminum-foil lined cylinders are also reviewed.-

Hanson, M. P.↗

A Brief Overview of the Effects of Impact Damage to Rocket Motor Cases

This Technical Memorandum (TM) presents pertinent results from past experimental work concerning impact damage to composite rocket motor cases. A rocket motor case in this TM refers to filament-wound pressure vessels of a substantial size intended to be used for launch vehicles, such as the new Space Launch System (SLS) rocket. In the early 1980s, as carbon fiber composites were becoming increasingly used on aircraft, concerns about the effects of foreign object impact damage grew, since the compressive strength properties of these composites could be severely affected by impact damage. The tensile properties were not as affected by foreign object impact damage which is fortunate for rocket motor cases as they are driven by tensile loads (burst strength). While great improvements to both carbon fibers and resins have resulted in far superior toughness values compared to the early generation of carbon/epoxy systems, the stigma of composite rocket motor cases being easily damaged and the burst strength compromised persists.

impact damage↗

Survey of long-term durability of fiberglass reinforced plastic structures

Included are fluid containment vessels, marine structures, and aircraft components with up to 19 years of service. Correlations were obtained for the variation of static fatigue strength, cyclic fatigue strength, and residual burst strength for pressure vessels. In addition, data are presented for the effects of moisture on strength retention. Data variations were analyzed, and relationships and implications for testing are discussed. Change in strength properties for complete structures was examined for indications of the effects of environmental conditions such as moisture and outdoor exposure (ultraviolet radiation, weathering) on long term durability.

Lieblein, S.↗

Use of Raman Spectroscopy and Delta Volume Growth from Void Collapse to Assess Overwrap Stress Gradients Compromising the Reliability of Large Kevlar/Epoxy COPVs

Composite Overwrapped Pressure Vessels (COPVs) are frequently used for storing pressurized gases aboard spacecraft and aircraft when weight saving is desirable compared to all-metal versions. Failure mechanisms in fibrous COPVs and variability in lifetime can be very different from their metallic counterparts; in the former, catastrophic stress-rupture can occur with virtually no warning, whereas in latter, a leak before burst design philosophy can be implemented. Qualification and certification typically requires only one burst test on a production sample (possibly after several pressure cycles) and the vessel need only meet a design burst strength (the maximum operating pressure divided by a knockdown factor). Typically there is no requirement to assess variability in burst strength or lifetime, much less determine production and materials processing parameters important to control of such variability. Characterizing such variability and its source is crucial to models for calculating required reliability over a given lifetime (e.g. R = 0.9999 for 15 years). In this paper we present a case study of how lack of control of certain process parameters in COPV manufacturing can result in variations among vessels and between production runs that can greatly increase uncertainty and reduce reliability. The vessels considered are 40-inch ( NASA Glenn Research center, Cleveland, OH, 44135 29,500 in3 ) spherical COPVs with a 0.74 in. thick Kevlar49/epoxy overwrap and with a titanium liner of which 34 were originally produced. Two burst tests were eventually performed that unexpectedly differed by almost 5%, and were 10% lower than anticipated from burst tests on 26-inch sister vessels similar in every detail. A major observation from measurements made during proof testing (autofrettage) of the 40-inch vessels was that permanent volume growth from liner yielding varied by a factor of more than two (150 in3 to 360 in3 ), which suggests large differences in the residual stress gradient through their overwraps. This resulted in large uncertainty in true fiber stress ratio (fiber stress at operating pressure divided by fiber stress at burst) which governs lifetime. The vessels were originally designed with tight safety margins, so it became crucial to develop a non-destructive evaluation (NDE) technique to directly measure the overwrap residual stress state of each vessel, and to identify those vessels at highest risk of having poor reliability. This paper describes a Raman Spectroscopy technique for measuring certain patterns of fluctuation in fiber elastic strains over the outside vessel surface (where all but one wrap is exposed at certain locations) that are shown to directly correlate to increased fiber stress ratios and reduced reliability.

Kezirian, Michael T.↗

A Study of Transparent Plastics for use on Aircraft. Supplement

This supplement to a NACA study issued in May 1937 entitled "A Study of Transparent Plastics for Use on Aircraft", contains two tables. These tables contain data on bursting strengths of plastics, particularly at low temperatures. Table 1 contains the values reported in a table of the original memorandum, and additional values obtained at approximately 25 C, for three samples of Acrylate resin. The second table contains data obtained for the bursting strength when one surface of the plastic was cooled to approximately -35 C.

Axilrod, Benjamin M.↗

The Effect of Calcium on the Cohesive Strength and Flexural Properties of Low-Methoxyl Pectin Biopolymers

Pectin binds the mesothelial glycocalyx of visceral organs, suggesting its potential role as a mesothelial sealant. To assess the mechanical properties of pectin films, we compared pectin films with a less than 50% degree of methyl esterification (low-methoxyl pectin, LMP) to films with greater than 50% methyl esterification (high-methoxyl pectin, HMP). LMP and HMP polymers were prepared by step-wise dissolution and high-shear mixing. Both LMP and HMP films demonstrated a comparable clear appearance. Fracture mechanics demonstrated that the LMP films had a lower burst strength than HMP films at a variety of calcium concentrations and hydration states. The water content also influenced the extensibility of the LMP films with increased extensibility (probe distance) with an increasing water content. Similar to the burst strength, the extensibility of the LMP films was less than that of HMP films. Flexural properties, demonstrated with the 3-point bend test, showed that the force required to displace the LMP films increased with an increased calcium concentration ( p < 0.01). Toughness, here reflecting deformability (ductility), was variable, but increased with an increased calcium concentration. Similarly, titrations of calcium concentrations demonstrated LMP films with a decreased cohesive strength and increased stiffness. We conclude that LMP films, particularly with the addition of calcium up to 10 mM concentrations, demonstrate lower strength and toughness than comparable HMP films. These physical properties suggest that HMP has superior physical properties to LMP for selected biomedical applications.

Biochemistry & Molecular Biology↗

A Study of Transparent Plastics for use on Aircraft, Special Report

Various transparent organic plastics, including both commercially available and experimental materials, have been examined to determine their suitability for use as flexible windshields on aircraft, The properties which have been studied include light transmission, haziness, distortion, resistance to weathering, scratch and indentation hardness, impact strength, dimensional stability, resistance to water and various cleaning fluids, bursting strength at normal and low temperatures, and flammability.

Axilrod, Benjamin M.↗

Comments on “Failure analysis of corroded hydrogen-blended natural gas pipelines based on finite element analysis and genetic algorithm-back propagation neural network” [262 (2025) 111174]

This is a brief commentary paper to highlight and discuss the determination of hydrogen concentration in pipeline steel, effect of hydrogen embrittlement (HE) on the mechanical properties of the material, burst strength of corroded pipelines using finite element analysis (FEA) simulations, and curve-fit models for assessing remaining strength of X80 corroded pipelines for transporting hydrogen blended natural gas. Recently, Xie et al. [1] proposed a methodology to quantify the impact of HE on material properties and numerically determined burst pressure of X80 corroded pipelines. However, their HE quantification overestimated the degradation of tensile strength for hydrogen blending ratios beyond the original data range, and their FEA results of burst pressure are nonconservative. This work thus recharacterized the hydrogen concentration in the steel pipeline and the effect of HE on tensile strength, and then redetermined burst pressures for a set of typical corrosion defect cases considered by Xie et al. [1] based on an experimentally validated FEA modelling method. With the new FEA results, two empirical corrosion models were proposed for X80 corroded pipelines for hydrogen service. At zero hydrogen blending ratio, the novel empirical models predict burst pressures to be consistent with the industry-accepted corrosion models. Furthermore, both the numerical simulation method and the novel corrosion models are significant contributions to the pipeline industry and the hydrogen community. Application of these results will enhance the safety, reliability, and integrity of natural gas pipelines when used to transport hydrogen.

Burst pressure prediction↗