## 2 Materials and Methods  
The determination of the stabilization temperature is based on several considerations. The surface of the specimen, which is the border between the specimen and the environment, is subject to a double heat exchange; in fact, on one hand, it absorbs the heat generated in the innermost parts of the specimen where the damage occurs; on the other hand, it transfers heat to the external environment, which is at a lower temperature. The surface temperature trend is therefore given by the balance between these two phenomena. The equation that governs heat transfer phenomena is the heat transfer law, or [PERSON]'s law, and it has the following Expression (1):  
\[\frac{Q}{\Delta t}=-h\cdot S\cdot(T(t)-T_{a}) \tag{1}\]  
where:  
* \(Q\) is the amount of heat generated inside the specimen at the instant of time \(\Delta t\);
* \(h\) is the transport or external conductivity coefficient, which depends on the nature of the body and the environment, the state of the contact surfaces and the environmental conditions;
* \(S\) is the thermal exchange surface;
* \(T_{a}\) is the temperature of the reference body, very often the environment;
* \(T(t)\) is the temperature of the body that is releasing heat at the instant t.  
The minus sign indicates that there is heat transfer to the environment if \(T(t)>T_{a}\) and vice versa if \(T(t)<T_{a}\). The solution of this differential equation is the typical one of the first order, namely:  
\[T(t)=T_{0}+\left(1-e^{-\frac{1}{t}}\right)\cdot(T_{1}-T_{0}) \tag{2}\]  
where \(T_{0}\) is the initial temperature. In terms of temperature variation, it is possible to rewrite the equation in the following way:  
\[\Delta T(t)=\left(1-e^{-\frac{t}{t}}\right)\cdot\Delta T_{1} \tag{3}\]  
where:  
* \(\tau\) is a constant indicating the speed of heat exchange;
* \(\Delta T(t)\) is the increase in surface temperature at the instant \(t\);
* \(\Delta T_{1}\) is the difference between \(T_{1}\), which is the limit temperature, and \(T_{0}\). The stabilization value, indeed, is given by:  
\[\underset{t\rightarrow\infty}{\text{lim}}\Delta T(t)=\Delta T_{1} \tag{4}\]  
The value of \(\Delta T_{1}\) is determined employing a best-fit operation. Interpolating the temperature values captured by the thermal camera with the function \(\Delta T(t)\) of Equation (3),the regression coefficients \(\Delta T_{1}\) and \(\tau\) will be calculated. This procedure thus avoids the impossibility of measuring the limit temperature experimentally. A routine in Matlab was used to process the thermal imaging camera acquisitions and to generate the thermal maps and the graphs for a first check of data. A further routine in Mathematica was used to exclude possible errors in the experimental data, such as drift or shift of the data, and to calculate the regression coefficients. The analysed material is an E-glass/epoxy composite. The specimens are obtained from two laminates, realized by the vacuum bag moulding technique, with a ply sequence of four fabric layers. The first one has a resulting thickness \(b\) of 2.2 mm and a ply sequence of four biaxial fabric layers with stacking sequence [0 90 90 0]\({}_{\text{xk}}\), while the second one has a thickness \(b\) of 4 mm and a ply sequence of four quadriaxial fabric layers with stacking sequence [0 +45 90 \(-\)45]\({}_{\text{xk}}\). The physical and mechanical properties of the constituent materials are shown in Table 1. Specimens were obtained from panels 1 and 2 according to the standard ASTM D3039 [18] and they were provided with opportune tabs allowing an efficient load transmission during test and avoiding, at the same time, damage of specimen caused by the grip system of the test machine. Notches of different geometries have been made on the specimens. In particular, the specimens of geometry I, II and III are shown in Figure 1 and were obtained from panel 1 (specimens AA01, AA02 and AA03) [19] while those of geometry IV and V (Figure 2) were obtained from panel 2 (specimens A4 and A11) [20].