Measuring the notched compressive strength of composite laminates: Specimen size effects

Large fibre reinforced composite structures can give much lower strengths than small test specimens, so a proper understanding of scaling is vital for their safe and efficient use. Small size (scale) specimens are commonly tested to justify allowable stresses, but could be dangerous if results are extrapolated without accounting for scaling effects. On the other hand large factors are sometimes applied to compensate for uncertainties, resulting in overweight designs. The most important variables of scaling effects on the strength of composites with open holes have been identified from experimental tests as notch size, ply and laminate thickness. In this study, these have been scaled both independently and simultaneously over a large range of combinations. The specimens are fabricated from commercially available (Hexcel Composites Ltd.) carbon/epoxy pre-impregnated tapes 0.125 mm thick (IM7/8552). The material is laid up by hand in unidirectional [04]ns with n = 2, 3, 4, and 8 (i.e., 2, 3, 4 and 8 mm thick) and multidirectional laminates; two generic quasi-isotropic lay-ups, one fabricated with blocked plies [45n/90n/−45n/0n]s and the other with distributed layers [45/90/−45/0]ns with n = 2, 4 and 8 are examined. It is shown that the critical failure mechanism in these laminates is in the form of fibre microbuckling or kinking. The unnotched compressive strength in unidirectional specimens thicker than 2 mm is found to be limited by the stress concentration developed at the end tabs and manufacturing induced defects in the form of ply waviness, fibre misalignment and voids rather than specimen size (scaling). In the open hole specimens, for both lay-ups, the strength reduction observed is due to hole size effect rather than specimen thickness or volume increase. The open hole (notched) compressive strength results obtained compare favourably to predictions by a linear softening cohesive zone fracture model developed in earlier work by the second author

U.S. Resort Spa Offerings: A State of the Industry Report

The spa industry has achieved staggering growth over recent years. In 2015, there were 21,020 U.S. spa locations, most common being day spas followed by resort/hotel spas. In 2002, the first hard data on the number of U.S. resort/hotel spa facilities was revealed to the public. Since that time, the number of resort/hotel spa facilities has grown an additional 56%. Regardless of the staggering growth and size of the resort spa market, there are very few studies to help increase our understanding of this promising industry. As the industry expands and the spa-goer becomes savvier, it is important to know the range of spa menu offerings. Fourteen data sets of industry and member reports by the International Spa Association were collected, analyzed, and appropriate data extracted to create a comprehensive overview of U.S. resort spa menu offerings. Findings reveal that all resort spas offered massage, skin care and body services in 2016. Salon services were offered by 90% of all resort spas, followed by fitness or sports activities (62%), mind, body and spirit (56%), hydrotherapy (47%), complementary therapies (29%), wellness programs (13%) and medically supervised services (11%). Most common menu offerings included Swedish, pregnancy, deep tissue, and stone massages; anti-aging, sensitive skin, brightening, exfoliating and men’s facials; body wraps and scrubs and nail services. The report provides a comprehensive look at the most recent descriptive data on resort spa offerings

Blood on the wind and the tablet of destinies: intertextuality in Anzû, Enūma eliš, and Erra and Išum

Enūma eliš and Erra and Išum are richly intertextual poems that both make sophisticated allusions to Anzû. Both do so in competitive ways: Enūma eliš re-shapes earlier motifs towards its goal of elevating Marduk and Babylon over the gods and cities that came before them, while Erra and Išum uses allusions to undermine the image of Marduk that Enūma eliš creates. Tiʼāmtu’s blood carried on the wind to announce Marduk’s victory, and the tablet of destinies which Tiʼāmtu fastens to Qingu’s chest are two well-known examples of borrowings from Anzû in Enūma eliš.. This article traces them through all three poems and shows how they are transformed in each. In the case of Enūma eliš the way that the poem deploys these allusions has previously been called clumsy because they stand out and do not appear to fit seamlessly into the narrative. Yet a closer analysis reveals that they have been much better integrated than is usually recognised, and their subtleties make important contributions to the programme of Marduk supplanting Ninurta. In Erra and Išum the chain becomes ever more complex: the motifs refer back to both their original contexts in Anzû as well as their occurrences in Enūma eliš, implying a self-conscious awareness and exploitation of techniques used by earlier poets

Recreation Benefits Sought by Activity and User Groups

This research tested the relationships between benefits sought during a recreation experience, recreation activities, and user group characteristics. The data comes from an on-site self-administered survey of visitors to 13 parks in Southeast Michigan. One way analysis of variance, Scheffe\u27s test, and Linear Regression were used to test the research objectives. The importance of different benefits varied according to user group characteristics and activities. Activity variables slightly outperformed group characteristics in predicting benefit ratings, with one exception. Groups with women rated nature enjoyment higher than men. Male only groups rated excitement higher. Socializing was rated more important by larger groups. Trail and winter activity participants sought exercise and nature enjoyment. Visitors engaged in general and water-related activities cited socializing and enjoying nature as most important

Modelling manufacturing deformations in corner sections made of composite materials

A three-step finite element model has been implemented to predict the spring-in of L-shaped parts. The material property development during the cure has been modelled as step changes during transitions between viscous, rubbery and glassy states of the resin. The tool-part interaction is modelled as a sliding interface with a constant sliding shear stress. The effect of various material and geometric variables on the deformation of L-Section parts are investigated by a parameter sensitivity analysis. The spring-in predictions obtained by the finite element method are compared to experimental measurements for unidirectional and cross-ply parts of various thicknesses and radii. Results indicate that although a 2D plane strain model can predict the spring-in measured at the symmetry plane fairly well, it is not sufficient to capture the complex deformation patterns observed. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav