MILLAN et al 2023a - Revision history

Marherna: Marherna moved page Review 961403762036 to MILLAN et al 2023a

2023-01-10T13:14:24Z

Marherna moved page Review 961403762036 to MILLAN et al 2023a

Marherna at 13:00, 10 January 2023

2023-01-10T13:00:28Z

Frovelm at 14:42, 1 September 2022

2022-09-01T14:42:57Z

Frovelm at 14:40, 1 September 2022

2022-09-01T14:40:23Z

Frovelm at 14:30, 1 September 2022

2022-09-01T14:30:44Z

Frovelm at 14:24, 1 September 2022

2022-09-01T14:24:00Z

Frovelm at 13:45, 1 September 2022

2022-09-01T13:45:28Z

Frovelm at 13:43, 1 September 2022

2022-09-01T13:43:30Z

Frovelm at 12:28, 1 September 2022

2022-09-01T12:28:39Z

Frovelm at 12:15, 1 September 2022

2022-09-01T12:15:23Z

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 <div class="center" style="width: auto; margin-left: auto; margin-right: auto;">
 ‡ Airbus Defense and Space. Getafe </div>
--->
+--><span id="_Toc87344102"></span>
-−
-'''ABSTRACT''': This paper describes the development of a FEM simulating methodology to predict the behavior of a carbon thermoplastic composite panel on fire tests. The panel has a metal bracket and a mechanical monotonic load is applied simultaneously to the fire event. The tool is aimed to capture the most relevant phenomena involved on this complex problem and to be focused on predicting time to bracket detachment under the applied load which is the most relevant results of such fire test.
-−
-In the problem, many different physics are involved. To account for the most relevant a coupled thermo-mechanical FEM has been selected and within it, a transient creep analysis. Most relevant parts of the simulation are the thermal model assumptions, the material mechanical constitutive model, temperature dependency of thermal and mechanical properties and the selection of a consistent failure criteria.
-−
-During the development of the simulating methodology precautions have been taken in order to identify a set of parameters conforming the available adjustments. Selecting a set of values for these parameters a selected test case can be correlated. Keeping these parameters values unchanged, similar cases can then be predicted by the methodology rather testing similar cases.
-−
-This initial paper focuses on the simulation tool development. For the moment only initial correlation and validation tasks have been performed. It is expected to complete and improve this research in the future augmenting the validity envelope of the simulation e.g. including pull loads and/or flame angles/distances. An insight on possible simplifications and enrichments of the tools are also provided in the paper.
-−
-'''KEY WORDS:''' Non-linear Numerical Simulation, Fire Tests, Flame Simulation, Thermoplastic Composites, Thermo-Viscoplastic Material Model.
-−
-<span id='_Toc87344102'></span>
 ==ACKNOWLEDGEMENTS==

← Older revision		Revision as of 14:42, 1 September 2022
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	[[File:Review_961403762036_7622_Imagen5.png]]		[[File:Review_961403762036_7622_Imagen5.png]]
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	It can be seen that isothermal contours are ellipses centered on cords (xo, yo) and with constant eccentricity Sx/Sy, figure 1. The absolute value used on the x variable has been included to ensure the plane x=0 has a symmetry regardless the value of xo. This is merely a numerical aid to be able to simulate half of the panel and it will not be difficult to avoid it for cases where symmetry cannot be ensured.		It can be seen that isothermal contours are ellipses centered on cords (xo, yo) and with constant eccentricity Sx/Sy, figure 1. The absolute value used on the x variable has been included to ensure the plane x=0 has a symmetry regardless the value of xo. This is merely a numerical aid to be able to simulate half of the panel and it will not be difficult to avoid it for cases where symmetry cannot be ensured.

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 Last, but possible most relevant, is the temperature scale factor. This will be modeled by the temperature increment approaching a peak temperature increment. The expression below summarizes flame effects used in the simulation.
-{| class="formulaSCP" style="width: 100%; text-align: center;"
-|-
+[[File:Review_961403762036_7622_Imagen5.png]]
-| <math>\frac{T(t,x,y)-T_{amb}}{T_{peak}-T_{amb}}=\left(1-e^{-\frac{t}{\tau_{flame}}}\right)e^{-\frac{1}{2} \left(\left(\frac{\vert x\vert -x_{0}}{S_{x}}\right)^{2}+\left(\frac{\vert y\vert-y_{0}}{S_{y}}\right)^{2}\right)}</math>
-|}
-[[File:Review_961403762036_3820_formula 1.png]]
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 '''Tpeak'''; Maximum temperature at which the flame/exhaust approaches with time.
-'''τ<sub>flame</sub>'''; Time constant of vertex temperature increment. At a time equal to τ<sub>FLAME</sub>, temperature increment reaches 63.2% of peak increment. Values has been derived from initial test correlations.
+'''τ<sub>FLAME</sub>'''; Time constant of vertex temperature increment. At a time equal to τ<sub>FLAME</sub>, temperature increment reaches 63.2% of peak increment. Values has been derived from initial test correlations.
 '''x<sub>0</sub> y<sub>0</sub>'''; Flame vertex location on panel.

← Older revision		Revision as of 14:30, 1 September 2022
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	\| <math>\frac{T(t,x,y)-T_{amb}}{T_{peak}-T_{amb}}=\left(1-e^{-\frac{t}{\tau_{flame}}}\right)e^{-\frac{1}{2} \left(\left(\frac{\vert x\vert -x_{0}}{S_{x}}\right)^{2}+\left(\frac{\vert y\vert-y_{0}}{S_{y}}\right)^{2}\right)}</math>		\| <math>\frac{T(t,x,y)-T_{amb}}{T_{peak}-T_{amb}}=\left(1-e^{-\frac{t}{\tau_{flame}}}\right)e^{-\frac{1}{2} \left(\left(\frac{\vert x\vert -x_{0}}{S_{x}}\right)^{2}+\left(\frac{\vert y\vert-y_{0}}{S_{y}}\right)^{2}\right)}</math>
	\|}		\|}
		+	[[File:Review_961403762036_3820_formula 1.png]]

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 ==INTRODUCTION==
-COMPOSITE MATERIALS ARE progressively taking an increasing portion of aerospace structures material. Recently, there has been increasing interest in applying these material to structures with fire protection requirements. This has been enabled by the commercial availability of high temperature thermoplastic carbon composites which shall be capable to withstand fire events demands at least until extinctors actuate. Modification of structures from metal, i.e. isotropic, to composites which, in general, are non-isotropic, requires a large amount of tests for sustentation and validation of the updated designs. This is particularly tough when considering structures that have fire protection requirements where tests are particularly demanding and especial facilities and equipment are required.
+Composite materials are progressively taking an increasing portion of aerospace structures material. Recently, there has been increasing interest in applying these material to structures with fire protection requirements. This has been enabled by the commercial availability of high temperature thermoplastic carbon composites which shall be capable to withstand fire events demands at least until extinctors actuate. Modification of structures from metal, i.e. isotropic, to composites which, in general, are non-isotropic, requires a large amount of tests for sustentation and validation of the updated designs. This is particularly tough when considering structures that have fire protection requirements where tests are particularly demanding and especial facilities and equipment are required.
 The key reference for fire protection test methods is the Federal Aviation Administration Advisory Circular AC-20-135 ref [1] which established test requirements to show fireproof and fire resistant capabilities required to show fire protection requirement compliance for engine and auxiliary power units (APU) areas.
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 {| class="formulaSCP" style="width: 100%; text-align: center;"
 |-
-| <math>\frac{T(t,x,y)-T_{amb}}{T_{peak}-T_{amb}}=\left(1-e^{-\frac{t}{\tau_{flame}}}\right) e^{-\frac{1}{2} \left(\left(\frac{\vert x\vert -x_{0}}{S_{x}}\right)^{2}+\left(\frac{\vert y\vert-y_{0}}{S_{y}}\right)^{2}\right)}</math>
+| <math>\frac{T(t,x,y)-T_{amb}}{T_{peak}-T_{amb}}=\left(1-e^{-\frac{t}{\tau_{flame}}}\right)e^{-\frac{1}{2} \left(\left(\frac{\vert x\vert -x_{0}}{S_{x}}\right)^{2}+\left(\frac{\vert y\vert-y_{0}}{S_{y}}\right)^{2}\right)}</math>
 |}

← Older revision	Revision as of 13:14, 10 January 2023
(No difference)

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 Laminate elastic properties will be used for simulating in the most general form of an anisotropic material stiffness matrix. Each term of the stiffness matrix will be varied with temperature using the same elasticity temperature dependency. This simplification of the stiffness variation with temperature does not significantly impact the objective of accounting the time to detachment since the elastic deformation at detachment is low compared with plastic and creep deformations. The simplification allows to retain at least one parameter in case correlation adjustment require to trim elastic deformation. The simplification can easily be avoided if other results become relevant and enough data are available to include different temperature variations along different directions.
 From the above engineering properties, the resulting transversely isotropic stiffness matrix at room temperature becomes [GPa];
 {| class="formulaSCP" style="width: 100%; text-align: center;"

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 <div class="center" style="width: auto; margin-left: auto; margin-right: auto;">
-J.M. MARTINEZ<sup>*</sup>, F.J. SAN MILLAN<sup>*</sup>, M.K. FROVEL<sup>*</sup>, F CABRERIZO<sup>*</sup>, M.A. DE LA TORRE<sup>*</sup>, F.LOPEZ<sup>+</sup>, D. BENITO<sup>+</sup>, A. LOPEZ<sup>+</sup>, R. TEJERINA<sup>‡</sup>, S.LOPEZ<sup>‡</sup>.</div>
+J.M. MARTINEZ<sup>*</sup>, F.J. SAN MILLAN<sup>*</sup>, M.K. FROVEL<sup>*</sup>, F CABRERIZO<sup>*</sup>, M.A. DE LA TORRE<sup>*</sup>, F.LOPEZ<sup>+</sup>, D. BENITO<sup>+</sup>, R. TEJERINA<sup>‡</sup>, S.LOPEZ<sup>‡</sup>.</div>
 <div class="center" style="width: auto; margin-left: auto; margin-right: auto;">