Table 7.

Top 20 most influential keywords in 3DP ranked by centrality and usage frequency.

Frequency-based classification				Centrality based classification
Ranking	Counts	Year	Keywords	Centrality	Year	Keywords
1	765	2012	3D printing	0.18	2013	biomaterial
2	765	2011	additive manufacturing	0.18	2016	reconstruction
3	201	2012	fabrication	0.17	2017	fused filament fabrication
4	174	2011	design	0.16	2016	alloy
5	172	2013	mechanical property	0.15	2013	tissue engineering
6	100	2015	scaffold	0.15	2016	evolution
7	95	2014	behavior	0.13	2014	model
8	92	2014	composite	0.12	2013	optimization
9	91	2008	rapid prototyping	0.11	2016	extrusion
10	89	2014	polymer	0.1	2015	3D printing
11	78	2014	model	0.09	2014	nanoparticle
12	71	2015	microstructure	0.08	2016	temperature
13	71	2017	performance	0.07	2014	polymer
14	70	2013	deposition	0.07	2015	construction
15	68	2014	Additive manufacturing	0.07	2015	fiber
16	67	2014	technology	0.07	2015	powder
17	61	2014	System	0.06	2008	rapid prototyping
18	59	2016	strength	0.06	2015	microstructure
19	58	2013	optimization	0.06	2016	rheology
20	52	2015	laser	0.05	2013	hydrogel