Potential Weight Benefits of IM7/8552 Hybrid Thin-Ply Composites for Aircraft Structures

Composite materials have increasingly been used for aerospace applications due to improved performance and reduced weight compared to their metallic counterparts. Inclusion of thin-ply material, plies with cured thickness half or less than standard-ply composites, have potential to improve performance and reduce structural weight further. The effect of thin-ply material on the weight of aircraft structure was investigated by examining wing cover weight reduction. To minimize the effects on manufacturing due to using thin plies, hybrid laminates were examined that used thin 45-degree plies to replace their standard-ply counterparts in laminates. Compression after impact (CAI) tests were conducted to examine the possible weight savings that could be gained by increasing the design allowables that were used to size the wing upper cover of a semi-span test article. A large increase in CAI strength was observed for quasi-isotropic hybrid laminates, whereas less improvement was seen for hard hybrid laminates such as found in the wing cover. For laminates design by CAI strength, weight savings of about 13% were found using the hybrid hard laminates compared to the standard-ply laminates. Whether similar weight savings could be expected for structure sized using tension after impact allowables will have to be investigated further. Notched specimens were tested to examine possible weight savings using hybrid laminates in regions that are sized using discrete source damage requirements. As expected, the hybrid laminate had marginal improvements over the standard-ply laminate for compression with a notch present. The hybrid laminate, however, exhibited about 20% lower strength than the standard-ply laminate counterpart for tension with a notch. The failure mode of the hybrid specimens was a brittle, self-similar crack, which differs from the standard-ply specimens that failed by significant amounts of delamination and fiber splitting. In light of the apparent reduction in notched tensile strength, additional investigation is required to assess the use of hybrid laminates for areas containing discrete source damage, and their effect on weight of such regions

Mohammed Ali Nicholas Sa’id: de esclavo a veterano de la Guerra Civil de los Estados Unidos

Muhammad Ali Sa’id, que tomó el nombre de Nicholas Said después de haber sido bautizado, procedía del estado musulmán de Borno en la década de 1850. Seguirá un periplo que le llevará a través del Sahara hasta La Meca, Istambul y San Petersburgo. Posteriormente viajó como criado por Europa occidental, el Caribe y Norteamérica. Su trayectoria desde que era hijo de un poderoso general y gobernador en Borno hasta su estatus esclavo en el Imperio otomano y, después, como sirviente libre entre la nobleza rusa, le llevó por último a alistarse en el 55º regimiento de Massachusetts integrado completamente por negros durante la Guerra Civil en los Estados Unidos.Muhammad Ali Sa’id, who was renamed Nicholas Said upon his baptism, came from the Muslim state of Borno in the 1850s, following an odyssey that took him across the Sahara, to Mecca, Istanbul and St. Petersburg. He susbsequently traveled as a valet through western Europe to the Caribbean and North America. His trajectory from the son of a powerful general and governor in Borno to his enslaved status in the Ottoman Empire and then to a position as a freed servant to Russian nobility ultimately led to his enlistment in the all-black 55th Massachusetts Regiment during the Civil War in the United States

A Complexity View of Rainfall

We show that rain events are analogous to a variety of nonequilibrium relaxation processes in Nature such as earthquakes and avalanches. Analysis of high-resolution rain data reveals that power laws describe the number of rain events versus size and number of droughts versus duration. In addition, the accumulated water column displays scale-less fluctuations. These statistical properties are the fingerprints of a self-organized critical process and may serve as a benchmark for models of precipitation and atmospheric processes.Comment: 4 pages, 5 figure

Preliminary Weight Savings Estimate for a Commercial Transport Wing Using Rod-Stiffened Stitched Composite Technology

A structural concept called pultruded rod stitched efficient unitized structure (PRSEUS) was developed by the Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body (HWB) aircraft configuration. While PRSEUS was an enabling technology for the pressurized HWB structure, limited investigation of PRSEUS for other aircraft structures, such as circular fuselages and wings, has been done. Therefore, a study was undertaken to investigate the potential weight savings afforded by using the PRSEUS concept for a commercial transport wing. The study applied PRSEUS to the Advanced Subsonic Technology (AST) Program composite semi-span test article, which was sized using three load cases. The initial PRSEUS design was developed by matching cross-sectional stiffnesses for each stringer/skin combination within the wing covers, then the design was modified to ensure that the PRSEUS design satisfied the design criteria. It was found that the PRSEUS wing design exhibited weight savings over the blade-stiffened composite AST Program wing of nearly 9%, and a weight savings of 49% and 29% for the lower and upper covers, respectively, compared to an equivalent metallic wing

Correspondence from E.B. Lovejoy, August 30, 1862

Correspondence from E.B. Lovejoy regarding absent soldiers from Androscoggin Countyhttps://digitalmaine.com/absent_soldiers/1018/thumbnail.jp

Correspondence from E.B. Lovejoy, August 01, 1862

Correspondence from E.B. Lovejoy regarding absent soldiers from Androscoggin Countyhttps://digitalmaine.com/absent_soldiers/1000/thumbnail.jp

A semi-analytical method for calculating rates of new sulfate aerosol formation from the gas phase

International audienceThe formation of new aerosol from the gas phase is commonly represented in atmospheric modeling with parameterizations of the steady state nucleation rate. Present parameterizations are based on classical nucleation theory or on nucleation rates calculated with a numerical aerosol model. These parameterizations reproduce aerosol nucleation rates calculated with a numerical aerosol model only imprecisely. Additional errors can arise when the nucleation rate is used as a surrogate for the production rate of particles of a given size. We discuss these errors and present a method which allows a more precise calculation of steady state sulfate aerosol formation rates. The method is based on the semi-analytical solution of an aerosol system in steady state and on parameterized rate coefficients for H2SO4 uptake and loss by sulfate aerosol particles, calculated from laboratory and theoretical thermodynamic data

Correspondence from E.B. Lovejoy, August 05, 1862

Correspondence from E.B. Lovejoy regarding absent soldiers from Androscoggin Countyhttps://digitalmaine.com/absent_soldiers/1009/thumbnail.jp