Optimization of thermal expansion and dimensional stability in calcium-borosilicate glass fiber (R-12)/epoxy laminates for aerospace applications

<jats:p> This work focuses on optimising the thermal expansion and dimensional stability of calcium-borosilicate (CaO-B <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> -SiO <jats:sub>2</jats:sub> ) glass fibre R-12 reinforced epoxy-934 laminates. Due to their superior mechanical strength, thermal performance, and durability, these laminates are widely used in the aerospace industry. R-12 glass fibre offers high tensile strength and enhanced thermal resistance, while Epoxy 934 resin ensures excellent adhesion and stability under thermal and mechanical stresses. The temperature of interest was selected as 80°C, representing the service limit, which is typical of operational simulations in aerospace conditions with an extreme working range of around 70°C. The fibre orientations tested were <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>[</mml:mo> <mml:mrow> <mml:mo> </mml:mo> <mml:mo>±</mml:mo> <mml:mn>0</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> <mml:mo>]</mml:mo> </mml:mrow> </mml:math> </jats:inline-formula> <jats:sub>5S</jats:sub> , <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>[</mml:mo> <mml:mrow> <mml:mo> </mml:mo> <mml:mo>±</mml:mo> <mml:mn>15</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> <mml:mo>]</mml:mo> </mml:mrow> </mml:math> </jats:inline-formula> <jats:sub>5S</jats:sub> , <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>[</mml:mo> <mml:mrow> <mml:mo> </mml:mo> <mml:mo>±</mml:mo> <mml:mn>30</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> <mml:mo>]</mml:mo> </mml:mrow> </mml:math> </jats:inline-formula> <jats:sub>5S</jats:sub> , <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>[</mml:mo> <mml:mrow> <mml:mo> </mml:mo> <mml:mo>±</mml:mo> <mml:mn>45</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> <mml:mo>]</mml:mo> </mml:mrow> </mml:math> </jats:inline-formula> <jats:sub>5S</jats:sub> , <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>[</mml:mo> <mml:mrow> <mml:mo> </mml:mo> <mml:mo>±</mml:mo> <mml:mn>60</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> <mml:mo>]</mml:mo> </mml:mrow> </mml:math> </jats:inline-formula> <jats:sub>5S</jats:sub> in a series of 13 experiments designed using Response Surface Methodology (RSM) and Central Composite Design (CCD) in Design-Expert software, to determine their effect on thermal expansion and dimensional stability. The model was experimentally validated, confirming its accuracy and demonstrating its reliability in optimising fibre-reinforced epoxy composites for aerospace applications. </jats:p>