Lighting Strike Protection Systems

refers to composites that are specifically made/modified to provide more than one functionality. Typically, composites' main functionality is structural

Nonlinear numerical modelling of lightning strike effect on composite panels with temperature dependent material properties

This paper presents a physics based modelling procedure to predict the thermal damage of composite material when struck by lightning. The procedure uses the Finite Element Method with non-linear material models to represent the extreme thermal material behaviour of the composite material (carbon/epoxy) and an embedded copper mesh protection system. Simulation predictions are compared against published experimental data, illustrating the potential accuracy and computational cost of virtual lightning strike tests and the requirement for temperature dependent material modelling. The modelling procedure is then used to examine and explain a number of practical solutions to minimize thermal material damage. © 2013 Elsevier Ltd.

NONLINEAR NUMERICAL MODELLING OF LIGHTENING STRIKE EFFECT ON COMPOSITE PANELS WITH TEMPERATURE DEPENDANT MATERIAL PROPERTIES

Lightning strike is one of the challenges that the aerospace industry is facing in an effort to increase the percentage of composite materials used in aircraft structures. Lightning strike damage is due to high orthotropic electric resistivity of the composite panels, which leads to high thermal loads that cause decomposition of the epoxy and delimitations of the laminates. Yet, experimental testing of lightning strike on aircraft panels is expensive due to the large number of design parameters that can control the inflicted damage. A coupled thermal-electrical finite element analysis is used to investigate the design variables space that can affect lightning strike damage on epoxy/graphite composite panels. The contribution of this study is modeling the composite panels’ material properties as temperature dependent, which was excluded by other researchers. A number of practical solutions to minimize the damage effect are proposed. Two set of experimental results are used to verify the numerical ones. One experimental set for plain composite panel, and second one for composite panels with joints

Multiphysics Simulation of Thermal Plasma Produced by Lightning Strike on Aircraft Structures

A novel numerical technique is proposed to model thermal plasma of microseconds/milliseconds time-scale effect. Modelling thermal plasma due to lightning strike will allow the estimation of electric current density, plasma pressure, and heat flux at the surface of the aircraft structure. These input data can then be used for better estimation of the mechanical/thermal induced damage on the aircraft structures for better protection systems design. Thermal plasma generated during laser cutting, electric (laser) welding and other plasma processing techniques have been the focus of many researchers. Thermal plasma is a gaseous state that consists from a mixture of electrons, ions, and natural particles. Thermal plasma can be assumed to be in local thermodynamic equilibrium, which means the electrons and the heavy species have equal temperature. Different numerical techniques have been developed using a coupled Navier Stokes – Heat transfer – Electromagnetic equations based on the assumption that the thermal plasma is a single laminar gas flow. These previous efforts focused on generating thermal plasma of time-scale in the range of seconds. Lighting strike on aircraft structures generates thermal plasma of time-scale of milliseconds/microseconds, which makes the previous physics used not applicable. The difficulty comes from the Navier-Stokes equations as the fluid is simulated under shock load, this introducing significant changes in the density and temperature of the fluid.

Symptom Free: Will the Law Strike a Knockout Blow on Concussion in Rugby

As the Six Nations rugby tournament approaches its half way stage, the usual media chatter on who might win go on to win the championship has been substituted by concern over a number of high profile, concussion-related injuries.

Genesis of the brecciated rocks from mid atlantic ridge hydrothermal systems : Lucky Strike (37º50’N) and Menez Gwen (37º50’N)

Tese de doutoramento, Geologia (Metalogenia), Universidade de Lisboa, Faculdade de Ciências, 2014

Centro Republicano Federal de Ponta Delgada: ideologia, organização e dinâmica (1880-1888)

A criação do Centro Republicano Federal de Ponta Delgada em 1880 inscreve-se nos projectos republicanos federalistas e insere-se no quadro do seu movimento expansionista. Com a publicação do periódico A Republica Federal vinculado ao republicanismo português, o Centro instituiu o seu órgão de imprensa e principal elemento propagandístico. As suas páginas foram portadoras das novas concepções políticas e o elemento impulsionador das novas ideologias propagadas por Teófilo Braga, candidato a deputado e figura titular deste Centro. A sua leitura mostra-nos o percurso e o posicionamento político-ideológico dos republicanos micaelenses, particularmente em Ponta Delgada. Enquanto espaço público politizado, A Republica Federal foi o principal palco dos debates e disputas partidárias na luta contra as instituições monárquicas e no combate pela destituição dos poderes há muito implantados. Apresenta-nos um trajecto de contestação à centralização do poder, à oposição e resistência com que se depararam os republicanos na tentativa de por fim aos privilégios e práticas de corrupção que permitiam um controle pernicioso dos processos eleitorais, abalando inevitavelmente o conservadorismo das elites locais com costumes e preconceitos difíceis de alterar. Foi no Centro Republicano Federal de Ponta Delgada e no seu jornal que convergiram os projectos de descentralização administrativa, foram eles os promotores e foco disseminador do ideário republicano federal, aglutinando as aspirações dos republicanos que pretendem instalar-se como sistema alternativo.

Winston Churchill and the General Strike

Exploring the myths and legends which surround Churchill's role in the 1926 General Strike this places his involvement in the events of that year within the context of his views of sympathy strikes from before the Great War. The continuing importance of these views is shown to explain the marked contrasts between Churchill's approach to the General Strike in May 1926 and his efforts to find a way to resolve the coal dispute which dragged on throughout the year.

Suomenmaan kartta : tärkeimmillä historiallisilla tiedoilla varustettu : lahja-lehti Kyläkirjaston kylälehden tilaajille vuosina 1885-1888 /

1 kartta neljällä lehdellä :, vär. ;, lehdet n. 57,5 x 38,5 cm

[Recueil.] Bal masqué du 11 février 1888

Collectionneur : Sirot, Georges (1898-1977)