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Stretchability and compressibility of a novel layout design for flexible electronics based on bended wrinkle geometries
摘要： A novel bended wrinkle structure is proposed for layout design in flexible electronics, which is formed by compressive local buckling of the thin film bonded onto a pre-strained, finite-thickness substrate upon release of the pre-strain. The excellent performance of stretchability of this structure, which could be as high as 309%, is shown according to theoretical analyses and validated by finite element method (FEM). Furthermore, the maximum strain of the proposed design is examined to ensure reliability of application devices. Except for the approach to compressibility based on maximum strain analyses, the bended wrinkle structure is taken as a laminate with geometrical imperfections and buckling analyses are conducted to obtain the critical buckling loads, consequently another evaluation criterion for compressibility is established. It is also revealed that the stretchability can be further enhanced by bonding the two ends of the structure to another pre-strained compliant basal substrate, though the pre-strain for the basal substrate is restricted by the compressibility. In the current work, an alternative to existing planar wavelike layout designs is presented and the results obtained offer important design guidelines for future applications.
关键词： Stretchability,Wrinkles,Compressibility,Buckling,Layout design,Flexible electronics
更新于2025-09-10 09:29:36
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Buckling and free vibration analysis of piezoelectric laminated composite plates using various plate deformation theories
摘要： A finite strip method was developed for buckling and free vibration analysis of piezoelectric laminated composite plates based on various plate theories such as Zigzag, Refined plate and other higher order shear deformation theory by variation of transverse shear strains through plate thickness in the form of parabolic, sine and exponential. The plate edge conditions are considered to be simply supported and the polynomial shape functions are used to evaluate the in–plane and out–of–plane deflection and rotation of the normal cross section of plates in transverse direction. Numerical results were obtained based on various shear deformation plate theories to verify the proposed method. The effects of length to thickness ratio and fiber orientation of cross–ply and angle–ply laminate were presented. Also, the effect of different electrical conditions on the critical buckling load under in–plane forces and strains is investigated and electrical buckling load and natural frequency of piezoelectric laminate composite plates are calculated through numerical examples. In addition, the new results on the effect of piezoelectric layers thickness, placement of piezoelectric layers and also the effect of length to thickness ratio in the interaction of biaxial in–plane loading on critical buckling load were studied.
关键词： Piezoelectric Layers,Free Vibration,RPT,Buckling,Zigzag theory
更新于2025-09-10 09:29:36
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B7 liquid crystal filament growth in the presence of carbon nanotubes
摘要： Liquid crystal phases formed from bent-core mesogens have attracted much interest of the liquid crystal research community, due to the manifestation of chirality effects from achiral molecules. One of the most elusive of the bent-core phases is the B7 phase, which at its early stage often forms in a helical filament fashion. We investigate the growth of such filaments in the presence of single-walled nanotubes to elucidate possible effects on the growth dynamics and helicity of B7 helical filaments. It is found that the filament width slightly decreases in comparison to the neat B7 material, suggesting a more tightly bound structure around the nanotubes, with the nanotubes likely acting as the core of the helical filament. No effects on pitch or periodicity of the helical superstructure is observed. The filament growth velocity quickly decreases as nanotubes are added to the B7 phase, indicating that a more tightly bound structure needs a longer time of formation. An observed buckling instability is of interest as a microscopic example for the study of nonlinear dynamics theories of filaments. The present investigation is thus of general importance for nanoparticle directed growth of filaments, which has applications in biomolecular growth and high tensile strength fibres.
关键词： bent-core mesogens,nanotubes,buckling instability,B7 phase,liquid crystal,filament growth
更新于2025-09-09 09:28:46
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Equi-biaxial compressive strain in graphene: Grüneisen parameter and buckling ridges
摘要： Here we report equi-biaxial compressive strain in monolayer graphene on SiO2 and Si3N4 substrates induced by thermal cycling in vacuum. The equi-biaxial strain is attributed to the mismatch in coefficient of thermal expansion between graphene and the substrate and sliding of graphene on the substrate. Importantly, the induced buckling ridges in graphene exhibit a pattern representing the symmetry of graphene crystal structure, which agreed well with our molecular dynamics (MD) simulations. Furthermore, these thermally-induced buckling ridges were found reminiscent of those in graphene synthesized by the CVD and SiC sublimation methods, suggesting the same origin of formation of the buckling ridges.
关键词： biaxial strain,thermal cycling,graphene,buckling ridges,molecular dynamics simulation,Grüneisen parameter
更新于2025-09-09 09:28:46
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Clinical Features and Surgical Outcomes of Primary Rhegmatogenous Retinal Detachment according to Age
摘要： Purpose: To investigate the clinical features and surgical outcomes of rhegmatogenous retinal detachment (RRD) requiring surgery according to age. Methods: Medical records of patients who underwent surgery for primary RRD between January 2008 and March 2016 were reviewed retrospectively. Patients were classified into two groups according to age at diagnosis: the under-40 group and the over-40 group. The two groups were compared in terms of demographic features, ocular manifestation, operating methods, primary anatomical success rate, and visual outcome. Results: One hundred and forty-four eyes from 144 patients were included. Mean subject age was 48.6 ± 16.9 years old. The under-40 group involved 42 eyes from 42 patients, and the over-40 group included 102 eyes from 102 patients. Symptom duration was shorter in the under-40 group compared to the over-40 group (7.6 ± 10.7 days vs. 14.5 ± 24.4 days; p = 0.029). Proliferative vitreoretinopathy (PVR) occurred more frequently in the under-40 group (40.0% vs. 17.4%, p = 0.007) than in the over-40 group. The anatomical success rate of primary surgery was significantly different between the two groups; 78.6% in the under-40 group and 91.2% in the over-40 group (p = 0.038). Preoperative PVR increased the rate of anatomical failure (40.0% vs. 6.2%, p < 0.001). The visual outcomes were not significantly different between the two groups. Conclusions: RRD is combined with PVR more frequently in young patients than in old patients, which increases the failure rate of primary re-attachment surgery.
关键词： Rhegmatogenous retinal detachment,Vitrectomy,Age,Scleral buckling,Proliferative vitreoretinopathy
更新于2025-09-09 09:28:46