Buckling strength improvements for Fibre Metal Laminates using thin-ply tailoring

The buckling response and load carrying capacity of thin-walled open cross-section profiles made of Fibre Metal Laminates, subjected to static axial compression loading are considered. These include thin-walled Z-shape and channel cross-section profiles adopting a 3/2 FML lay-up design, made of 3 aluminium layers. The objective of the investigation is the comparison of standard thickness Fibre Reinforced Plastic layers versus thin-ply material technology. Whilst thin ply designs differ only by the layer thickness, they offer an exponential increase in stacking sequence design freedoms, allowing detrimental coupling effects to be eliminated. The benefit of different hybrid materials are also considered. The comparisons involve semi-analytical and finite element methods, which are validated against experimental investigations

Tapered laminate designs for new non-crimp fabric architectures

Non-Crimp Fabric (NCF) materials are now available in a range of areal weights and layer architectures, including 0/45, 0/−45, 45/−45 and 0/90, which correspond to the standard ply orientations employed in traditional UD material lay-ups. The benefit of NCF material is generally associated with increased deposition rate, but this advantage may be offset by reduced design freedoms when a specific form of mechanical coupling behaviour is required, layer terminations must be introduced and/or thermal warping distortion eliminated. This article investigates the extent to which new NCF architectures can be tailored to achieve warp free tapered laminates with mechanical Extension-Shearing Bending-Twisting coupling, by single axis (longitudinal) deposition of all ply angles; thus avoiding ply discontinuities that may be introduce in large component manufacture. Lamination parameter design spaces are used to demonstrate the extent of the feasible solutions both before and after applying a laminate tapering scheme

On extension-shearing bending-twisting coupled laminates

This article presents details of the development of a special class of laminate, possessing Extension-Shearing Bending-Twisting coupling, necessary for optimised passive-adaptive flexible wing-box structures. The possibility of achieving a measurable drag reduction in cruise flight, without the cost or reliability issues associated with active control mechanisms, is of significant interest for achieving increased fuel burn efficiency, and meeting associated emissions targets. The introduction of passive Bending-Twisting coupling at the wing-box level has been previously demonstrated through laminate level tailoring with Extension-Shearing coupling only, but the limited design space and the possibility for ply terminations (to produce tapered thickness) effectively rule out this special class of laminate for practical construction. The study is now broadened to consider laminates with Extension-Shearing and Bending-Twisting coupling, beyond the less well-known un-balanced and symmetric design rule or indeed balanced and symmetric designs with off-axis alignment. Results reveal a vast laminate design space with Extension-Shearing coupling that can be maximised without the unfavourable strength characteristics associated with off-axis alignment. Results also reveal that shear buckling strength can be maximised through Bending-Twisting coupling when load reversal is not a design constraint

Effect of bending-twisting coupling on the compression and shear buckling strength of infinitely long plates

This article describes the development of closed form polynomial equations for compression and shear buckling to assess the effect of Bending-Twisting coupling on infinitely long laminated plates with simply supported edges. The equations are used to generate contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The contour maps are applicable to two recently developed databases containing symmetric and non-symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide new insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying common design heuristics, including ply angle, ply percentage and ply contiguity constraints

Tapping the Voices of Learners for Authentic Student Engagement

The purpose of this study was to examine the problem of practice of the decline in student engagement from the perceptions of secondary school learners as they proceed throughout their educational experience. According to researchers, learners who are engaged—meaning those who are committed and connected in active relationships with teachers, other learners, the learning environment, learning interests and ideas, the curriculum, and learning goals, are more likely to enjoy and be in control of their own learning [student agency]. This study is significant because of its potential to provide new understandings of the problem of a decline in student engagement from the perceptions of learners themselves. Therefore, this study qualitatively explored a purposeful sample of secondary school learners’ perceptions regarding the phenomenon of student engagement during their secondary school experience. The purpose of a phenomenological qualitative research approach is to understand and describe the essence of some phenomenon by capturing the common experience of the phenomenon among a group of research participants. Subsequently, meaning can be constructed out of the common experience of the group. By listening to the voices of learners, a greater understanding could be developed for confronting the life-altering concern of a lack of student engagement in learning during the secondary school experience. Since researchers have found student engagement in school can transfer to academic, emotional, economic, and social success in school, college, career, and life, understanding what personally engages learners holds significant weight for all students. Gaining a clearer picture in the local context of what engages secondary students from the perceptions of learners could provide a deeper understanding for establishing access to personalized student learning environments, experiences, and opportunities

Addressing Urban Income Inequality Through Education: A Case Study in Atlanta

For decades, the income inequality gap between the rich and poor has continued to expand dramatically, with criticism of existing education systems often at the heart of the issue. Large urban cities are commonly at the forefront of the issue, given the plethora of teacher strikes in recent years. Events such as the 11-day Chicago teacher’s strike in October of 2019 that idled academics and college prep for 350,000 students, have highlighted many current education issues (Hauck, 2019). With underfunded and poorly equipped middle and high schools, students in poor and minority neighborhoods in cities are less prepared academically, ill equipped to secure college acceptance, and lack the financial resources available to effectively pursue higher education (Haveman & Smeeding, 2006). Studies conducted by Chetty (2010) and Duncan (2017) have shown a strong link between access to education and income inequality. As Atlanta ranks worst in large city income inequality nationwide and consistently struggles with poverty rates around 25%, it will be the focus of this proposed city plan to explore existing poverty issues through the scope of education (Gongloff, 2017). Proposals are then given for education reforms to help combat income inequality through educational mobility. The overall targets of these reforms are to combat the initial gap in opportunities for students, the overall long-term income potential of low-income students, and improvements in teacher quality in Atlanta and urban schools overall

Effect of Design Heuristics on the Compression and Shear Buckling Performance of Infinitely Long Plates With Bending-Twisting Coupling

This article investigates the effect of design heuristics, including ply percentages and ply contiguity constraints, on the compression and shear buckling performance of Bending-Twisting coupled infinitely long laminated plates with simply supported edges. The buckling solutions are presented as contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The applicability of the results extends beyond the current certification envelope, comprising symmetric laminate configurations. Indeed, the contour maps are applicable to two recently developed databases containing non-symmetric and symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying design heuristics