Overview of Thermal Expansion of Metal Fabric (Stainless Steel)
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“Deformation Due to Thermal Expansion of Metal Fabric”
REDM. SCIENCE FOR YOU!
2015.06.15 ReDM Technical Department
The base material of the metal fabric is Stainless Steel of the 300 series (austenitic), which, as widely known, offers economic advantages, corrosion resistance, ease of processing, aesthetic appeal, and relatively low deformation due to thermal expansion.
These characteristics make it one of the most favored materials in modern construction.
However, as is known, when applied to exterior use, there is insufficient information regarding damage and elongation caused by thermal deformation, especially due to external environmental factors like temperature.
As such, while brief, this explanation is intended to share knowledge and information and to motivate further improvement through suggestions and advice from experts.
1. Understanding Thermal Expansion of Metal Fabric
Thermal (linear) expansion rate : L=L0(1+a* △t)
L : Increased length of the material
L0 : Original length of the material
△t : Temperature change
a : Coefficient of thermal expansion for stainless steel : 17.3 10-6 ℃)
Here, the thermal expansion of metal materials can be further categorized into volumetric expansion, linear expansion, and more, but since the material of the metal fabric is stainless steel wire (ROD and ROPE), we have based the calculation on linear expansion.
※ Example based on the ReDM 4350 pattern specifications.
Length(mm)/ ℃ |
10 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
100 |
1.000 |
0.17 |
0.35 |
0.52 |
0.69 |
0.87 |
1.04 |
1.12 |
1.38 |
1.56 |
1.73 |
5.000 |
0.85 |
1.75 |
2.60 |
3.45 |
4.35 |
5.20 |
6.05 |
6.90 |
7.90 |
8.65 |
10.000 |
1.70 |
3.50 |
5.20 |
6.90 |
8.70 |
10.40 |
12.10 |
13.80 |
15.80 |
17.30 |
Assuming that the highest surface temperature of the metal in midsummer rises above 70°C, we can predict that a metal fabric used for an exterior facade on a 3-4 story building will expand by approximately 12mm along its length direction.
(Of course, the wires in the transverse direction will also expand, but this is assumed to be absorbed by the joints between the fabric panels. Additionally, while volumetric expansion can also be considered, this is excluded from this calculation.)
Considering that most of the metal fabric installation styles in Korea involve the fabric being tightly pulled both vertically and horizontally, under extreme heat, the fabric may experience slight elongation.
This could lead to claims from some consumers who do not consider the inherent properties of metal fabric.
However, there is an important aspect that has not been considered here, which is outlined below.
2. Understanding the Structure of the Raw Material (Wire Rope-Cable) of Metal Fabric
1) Typically, the wire rope used for metal fabric has a 7x7 steel wire structure with a 2.0mm diameter.
This means that 49 thin stainless steel wires are twisted alternately in the left and right directions to form the 2.0mm rope.
This process creates small gaps between the wires, and considering that the primary material of the metal fabric is cable, these spaces can absorb or buffer any deformations (contraction, expansion).
2) As mentioned, the metal fabric cable consists of bundles of wire strands rather than rods.
This structure allows the diameter of the rope to flex under external pressure.
Therefore, it can act as a buffer when length deformations occur.
3. Understanding the Installation Method of Metal Fabric
Metal fabric installation is generally performed by experienced professionals with over 10 years of expertise.
Due to the wide variety of patterns and the varying specifications based on the target building, the installation methods and details can differ greatly.
As a result, the installation is carried out by highly skilled professionals who have accumulated experience and knowledge. They ensure that the fabric is installed with sufficient tension.
As a result of this skilled installation, deformation due to thermal expansion has not been a cause for concern or defect over the past 10 years, except in special cases.
In cases where the installation area is particularly large or subject to external environmental factors such as wind pressure, design support from a technical team can address potential issues by applying various details such as spring-type (spring type, rod bar type) solutions.
Ultimately, while metal fabric may not always be a product made to precise millimeter specifications, REDM’s philosophy is to address consumer concerns through active research and development.
Expanding and applying metal fabric beyond its design limits, these efforts accumulate and, ultimately, the only way to gain consumer trust and understanding is through technical excellence. REDM will continue to develop and work hard to meet the expectations of those who support and show interest in the company.
