Terahertz Spectroscopic Characterization and Thickness Evaluation of Internal Delamination Defects in GFRP Composites

Chinese Journal of Mechanical Engineering

Table 2 Presentation of the real and the experimental values of thickness for the different delamination defects for 5 samples with the standard error (SE) and relative error

Sample number	The top delamination			The middle delamination		The bottom delamination
Sample number	Real (µm)	Experimental (µm)	Relative error (%)	Experimental (µm)	Error (%)	Experimental (µm)	Error (%)
1	130	131.665	1.281	132.825	2.173	133.405	2.619
2	130	130.505	0.388	131.085	0.835	132.245	1.727
3	130	129.925	− 0.058	130.505	0.388	130.505	0.388
4	130	130.505	0.388	131.084	0.834	129.344	− 0.504
5	130	130.505	0.388	129.924	− 0.058	130.505	0.388
Mean ± SE	130 ± 0	130.621 ± 0.284	–	131.085 ± 0.485	–	131.201 ± 0.720	–

Note: The real thickness values here are the values measured by the micrometer while the experimental values designate the values measured by the THz-TDS