Investigation and simulation of temperature changes and thermal deformations of multilayered structure with gypsum plate/Daugiasluoksnes konstrukcijos su gipso plokste temperaturos pokyciu ir temperaturiniu deformaciju tyrimas ir modeliavimas.
Guobys, R. ; Vekteris, V. ; Moksin, V. 等
1. Introduction
Modern fire resistant multilayered structures must be able to
withstand temperatures up to 360[degrees]C in order to protect the
escaping routes and escaping people against fire [1]. Wooden structures
exhibit good thermal insulation properties, but their protection time
interval is limited due to the high combustion rate of the wood (about 2
mm/min [2, 3]. Therefore such structures must be made of less
combustible materials. In some cases gas and polymer fillers [4] are
used in the structures, but these structures are expensive and
complicated. Gypsum is one of the cheapest materials that has very good
thermal insulation properties and can resist the spread of fire.
This work investigates the thermal behaviour of fire resistant
multilayered structure containing gypsum plate.
[FIGURE 1 OMITTED]
2. Object of investigation
Fire resistant multilayered structure (Fig. 1, a, dimensions H x W:
2100 x 980 mm) consisting of outer 1 mm thick steel sheet, 10 mm thick
gypsum plate, 50 mm thick stone wool (density 140 kg/[m.sup.3]) layer
and 1 mm inner thick steel sheet was chosen as an object of
investigation. A door was installed into the brick wall fastened to the
furnace as shown in Fig. 1, b. Because the investigated structure is
asymmetrical with respect to the vertical centre plane, it was
investigated under different fire conditions. In the first case (shown
on the right side (from the viewer's perspective) of Fig. 1, b)
gypsum layer was located closer to the flame than stone wool layer. In
the second case (shown on the left side (from the viewer's
perspective) of Fig. 1, b), stone wool layer was closer to the heat
source.
3. Experimental procedure and results
High-temperature tests were conducted in special gas-fired fire
test furnace under real fire conditions [1]. The furnace temperature was
controlled using six thermocouples distributed evenly inside the
furnace. Thermocouple signals are transmitted to the computer, which
compares measured and programmed temperature values and controls the
fuel valve of the furnace.
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
Initial temperature inside the furnace at the beginning of the test
was equal to 13[degrees]C. Then it was increased according the
recommendations [5]. Pressure inside the furnace was kept constant (20
Pa) throughout the whole experiment.
[FIGURE 4 OMITTED]
Temperature of the door was measured by thermoelements attached to
the door at measuring points 1-26 (Fig. 1) according to the
recommendations [6]. Temperature at the points 1-5 and 14-18 during the
testing should not exceed 180[degrees]C, temperature of the remaining
points should not exceed 360[degrees]C otherwise the experiment is
considered as failed, because fire penetration through the structure can
occur. The structure is considered as unable to ensure protection of
premises and escaping from building people against thermal effects.
Thermal deformations of the door were measured with respect to the
wall at the points D1-D11 shown in Fig. 1, a. For that purpose three
horizontal steel strings were attached to the wall before the
investigated structure, these strings are seen in Fig. 1, b. Thermal
deformations of the structure were measured with respect to these
strings by means of the calliper. Thermal deformations analysis is very
important for such segmental structures, consisting of separate stone
wool panels, a gap between segments can be created due to large
deformations of the structure. These gaps sufficiently increase the risk
of fire penetration and spread.
Temperatures versus time curves are presented in Figs. 2 and 3. The
test was terminated after 60 min.
Thermal deformation values measured at the points D1-D11 at the end
of the test are presented in Table.
Thermal deformation measured at the centre point of the structure
versus time curves are presented in Fig. 4.
Temperature at the door points 14-18 increased to 92[degrees]C
during the period of 14 min then fell to 57[degrees]C (Fig. 2). The
structure "cooled itself due to the layer combination during the
period of 20 min. The cooling rate was about 2[degrees]C/min. Then
temperature raised evenly approximately at 1.5[degrees]C/min rate. The
effect of self-cooling was observed for the whole structure, not only
for points 14-18. Temperature at the points 19-22 decreased slightly
(about 15[degrees]C only), less as compared to the points 14-18. In case
shown on the right side of Fig. 1, b no self-cooling effect was observed
(Fig. 3).
Thermal deformations at the centre point of the structure shown on
the right side of Fig. 1, b were insufficient for practical
applications. Maximum value of 4 mm was reached at the end of the test
(Fig. 4, curve 1). In case shown on the left side of Fig. 1, b the
deformation reached 12-13 mm at the end of the test (Fig. 4, curve 2).
4. Numerical analysis
Simulations of thermal behaviour of the structure were performed
using SolidWorks[R] Simulation software. The case shown on the right
side of Fig. 1, b was chosen for further numerical analysis only. In
this case the structure demonstrated useful self-cooling properties and
exhibited less thermal deformations compared with the case shown on the
left side of Fig. 1, b.
Peculiarities of the structure and contact properties between
layers [7, 8] of the structure were evaluated through simulations.
Results of the simulation are presented in Figs. 5 and 6. It is evident
from Fig. 5 that temperature graph obtained from the simulation tends to
coincide with experimental one (Fig. 2). Calculated thermal deformation
values (Fig. 6, Table) are in good concordance with experimental data
presented in Table.
[FIGURE 5 OMITTED]
[FIGURE 6 OMITTED]
5. Conclusion
Results of numerical finite element analysis of multilayered
structure with gypsum plate are found to be in good agreement with
experimental results. This shows the suitability of numerical methods
for the analysis of thermal behaviour of such type structures.
References
[1.] Guobys, R.; Vekteris, V. 2009. Temperature deformation tests
of multilayer mechanical structures, Proceedings of the 14th
international conference "Mechanika-2009", April 3-4, 2008,
Kaunas, Lithuania: 116-121.
[2.] Joyeux, D. 2002. Experimental investigation of fire door
behaviour during a natural fire, Fire Safety Journal 37(6): 605-614.
http://dx.doi.org/10.1016/S0379-7112(02)00003-6.
[3.] Ghazi Wakili, K.; Wullschleger, L.; Hugi, E. 2008. Thermal
behaviour of a steel door frame subjected to the standard fire of ISO
834: Measurements, numerical simulation and parameter study, Fire Safety
Journal 43(5): 325-333. http://dx.doi.org/10.1016/j.firesaf.2007.11.003.
[4.] Linteris, G.T.; Rafferty, I.P. 2008. Flame size, heat release,
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[5.] European Standard EN 1363-1. Fire Resistance Tests: General
Requirements. Brussels: European Committee for Standardization (CEN),
2000.
[6.] European Standard EN 1634-1. Fire Resistance Tests for Door
and Shutter Assemblies--Part 1: Fire Doors and Shutters. Brussels:
European Committee for Standardization (CEN), 2000.
[7.] Kayhani, M.H.; Abassi, A.O.; Sadi, M. 2011. Study of local
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and heat generation, Mechanika 17(1): 57-63.
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[8.] Nazari, M.B.; Shariati, M.; Eslami, M.R.; Hassani, B. 2010.
Meshless analysis of cracked functionally graded materials under thermal
shock, Mechanika 4(84): 20-27.
R. Guobys *, V. Vekteris **, V. Moksin ***
* Vilnius Gediminas Technical University, J. Basanaviciaus 28,
03224 Vilnius, Lithuania, E-mail:
[email protected]
** Vilnius Gediminas Technical University, J. Basanaviciaus 28,
03224 Vilnius, Lithuania, E-mail:
[email protected]
*** Vilnius Gediminas Technical University, J. Basanaviciaus 28,
03224 Vilnius, Lithuania, E-mail:
[email protected]
doi: 10.5755/j01.mech.18.3.1878
Table
Thermal deformations of the structure at
the end of the test (case shown on the
right side of Fig. 1, b)
Measuring point Deformation value, mm
(Fig. 1, a)
Measured Calculated
D1 10 10
D2 8 9
D3 13 12
D4 2 2
D5 0 0
D6 4 4.5
D7 5 6
D8 3 2.5
D9 3 2.5
D10 -8 -8
D11 -1 0
Note: The negative sign means that the
deformation occurs in direction to the
heat source, otherwise it is positive
