## 3 Results and Discussion  
The multifunctional flexural-electrical performance of 3D printed composite coupons was characterized using a mechanical testing machine and a Keysight B2987A Electrometer. The experimental results showed that the test specimen exhibited an ultimate load of 178.7 N with a corresponding maximum deflection of 0.0089 m, a corresponding maximum flexural stress of 271 MPa, and a maximum strain of 0.0202 m/m. The reported value of the maximum flexural stress was 271 MPa with the maximum strain of 0.0202 m/m. Figure 1: Schematic details of the multifunctional flexural-electrical characterization test at RTD. Figure 2: Failed test coupons after the multifunctional flexural-electrical characterization test at RTD. The recorded maximum resistance was 55.1 G Ohms as a multifunctionality property. As shown in Figure 2, a lateral tensile failure mode that is perpendicular to the longitudinal axis of the coupons was induced along its lower side in the outer fibers of the test coupons. This failure mode was found to be consistent with the failure mode from the flexural testing of the monofunctional carbon fiber composites conducted at an ambient temperature. This harmony of the failure modes of the 3D printed multifunctional continuous carbon fiber composites and that of the traditionally manufactured carbon fiber composites suggests that the multifunctional continuous carbon fiber composites are suitable for structural applications in aerospace. Figures 3-5 summarize the multifunctional performance of the 3D printed continuous carbon fiber solid laminate composites test coupons. Figure 3 shows the loading versus time, and Figure 4 shows stress versus strain, while Figure 5 shows resistance versus strain of the test coupons. Figure 3 shows the loading versus time behavior of the 3D printed multifunctional continuous carbon fiber composites test coupons at RTD with step-wise function of loading on time scale to depict the time required for the electrometer settling times. The settling times are defined as the times it takes to settle and calm the fluctuations of the oscillations on the electrometer. The settling times needed for this study could have been attributed to the fact that the test coupons are highly resistive in nature. The loading versus time  
Figure 3: Loading versus time behavior of multifunctional test coupons at RTD: (**a**) 6207-00303; (**b**) 6207-00304; and (**c**) 6207-00305.  
behavior of the 3D printed multifunctional continuous carbon fiber composites was also analyzed to assess the effects of the settling times on the failure loads of the test coupons. Figure 4 shows the strain-strain behavior of the 3D printed multifunctional continuous carbon fiber composites test coupons at RTD. It was found that the stress-strain performance of the 3D printed multifunctional continuous carbon fiber solid laminated composites is consistent with the stress-strain behavior of the traditionally manufactured carbon fiber solid laminate composites. The maximum flexural stress of 271 MPa and the maximum ultimate load of 178.7 N were induced by 6207-00305. Table 1 summarizes the experimental test results with an average maximum flexural stress of 247 MPa and an associated maximum strain of 0.0195 m/m. The experimental test results showed that the 3D printed solid laminate test coupons exhibited an average ultimate load of 168.7 N and contributed to an average deflection of 0.0085 m at the ultimate load (as shown in Table 1). Table 2 shows the summary of the maximum resistance values of each test coupon at the RTD. As shown in Figure 5, the strain corresponding to the peak resistance value for 6207-00303, 6207-00304, and 6207-00305 was higher than the failure strain on each of those test coupons. Similarly, the strain at peak resistance value when compared to the respective failure strain was found to be 95.11% higher than the corresponding failure strains for test coupon 6207-00303.