## 2 Methods: Experiment and Numerical Simulation  
### Low-Velocity Impact Experimental Tests  
In the impact experimental tests, the testing composite specimen has the dimension \(L_{x}\times L_{y}\times L_{z}=100\) mm \(\times\) 100 mm \(\times\) (\(n\times\) 0.2 mm), in which \(n=16\) is the ply number of the glass fiber in the laminate. Composite laminates are composed of SMAs, glass fiber, and epoxy resin by a vacuum-assisted resin injection (VARI) process. SMA wires adopted super-elastic 55.9 wt.% Ni balance Ti wire with the diameter of 0.2 mm obtained from Jiangyin Fasten-PLT Materials Science Co., Ltd., Jiangsu, P.R. China. The glass fiber (GF) is unidirectional glass fiber (EDW800) with the layer thickness of 0.2 mm and the mass surface density of 200 g/m\({}^{2}\). It was provided from Jiangsu Jiuding New Material Co., Ltd., Nantong, Jiangsu, P.R. China. The selected resin is epoxy vinyl ester resin (VER) 411, in which the matching curing agent and accelerating agent are methyl ethyl ketone peroxide (MEKP) and dimethylaniline; it was bought from Harbin Akihito composite material Co., Ltd., Harbin, P.R. China. Figure 1a represents the pure fiber-reinforced laminate with the stacking sequences of [0/90]s, and Figure 1b represents the SMA and fiber hybrid-reinforced laminates with the stacking sequences of [(0/90)\({}_{4}\)/SMA/(0/90)\({}_{4}\)], [0/SMA/90/(0/90)\({}_{7}\)], [0/SMA/90/(0/90)\({}_{3}\)/SMA/(0/90)\({}_{4}\)], respectively. Here, the stacking sequence mentioned above is from bottom to up, where the subscript indicates repeated times, and the numbers 0 and 90 are the ply angles of each layer glass fiber, in which the angles of 0 and 90 correspond to x and y directions (see Figure 1). In this work, the SMAs are stitched in laminate by two types: one is the whole surface (Figure 1c), and the other is the local surface (Figure 1d), and the SMA wires always parallel to the direction of the 0\({}^{\circ}\) fiber layup direction in all specimens. The diameters of SMAs is 0.2 mm, and the interval spacing between the two SMAs is 5 mm for all of the specimens. The thicknesses of laminates for all specimens mentioned above are all 3.2 mm.  
The low-velocity impact tests are carried out by using a drop weight impact testing machine of Instron Dynamup 9250 HV followed by ASTM D7136/D7136M-07, which is a standard test method for measuring the damage resistance of a fiber-reinforced polymer matrix composites to a drop-weight impact event. The hydraulic fixing device and circular clamp with a diameter of 76 mm are used  
Figure 1: Schematic diagram of stacking sequence of hybrid composite laminates and impact region. SMA: shape memory alloy.  
to fix the specimens. A semispherical rigid impactor with a diameter of 14 mm and a total weight of eight kilograms (error \(\pm\)0.1 kg) are used in the low-velocity impact tests. The impact energies in the low-velocity impact tests are 32 J and 64 J, respectively, and the relevant parameters of the hybrid composite laminates and the initial impact energy are listed in Table 1. Further details on the manufacturing process and low-velocity impact experimental tests of composite laminates are described according to the previous work of our research group [21].