Tensile behavior of C⁃shape thin⁃walled structural parts fabricated by unsupported fused deposition modeling.

doi:10.19491/j.issn.1001-9278.2025.10.013

Abstract

Abstract:

This study investigates the tensile behavior of C⁃shaped thin⁃walled structural parts fabricated via unsupported fused deposition modeling （FDM）. Combining finite element simulation with static tensile testing of ABS and PC specimens， the influence of intrinsic structures on mechanical properties， stress distribution， and failure mechanisms was systematically analyzed. An orthogonal experimental design， fracture morphology analysis， and three⁃factor ANOVA were employed to evaluate the effects of geometry. Key findings established a minimum allowable unsupported printing angle of 16.53 °. Among the geometries tested， concave structures exhibited the highest elastic modulus. An optimal wall thickness of 5 mm was identified， outperforming 3⁃ and 4⁃mm configurations. While the slope of the structure had no significant effect on the elastic modulus， the height （and consequently the rotation radius） was a critical factor. This difference in rotation radius dictated the failure location： fractures initiated at smaller radii in straight and convex structures， but at larger radii in concave structures. This study provides crucial design guidelines for optimizing the mechanical performance of unsupported FDM thin⁃walled structures.

Key words: fused deposition modeling, mechanical properties, thin?walled structure

CLC Number:

TQ320.5

GUAN Tianmin, LI Xin, GUO Zefang, WU Guanying, ZHAI Yun. Tensile behavior of C⁃shape thin⁃walled structural parts fabricated by unsupported fused deposition modeling.[J]. China Plastics, 2025, 39(10): 76-84.

Figures/Tables 21

Fig.1. Condition settings for finite element analysis

Fig.2. Generatrix of samples

旋转体的母线	母线对应斜率
$y = 2 x$	2
$y = 3 x$	3
$y = 4 x$	4
$y = x 2 10$	0
$y = x 2 8$	0
$y = x 2 6$	0
$y = 5 (4 x)$	$∞$
$y = 5 (6 x)$	$∞$
$y = 5 (8 x)$	$∞$

旋转体的母线	母线对应斜率
$y = 2 x$	2
$y = 3 x$	3
$y = 4 x$	4
$y = x 2 10$	0
$y = x 2 8$	0
$y = x 2 6$	0
$y = 5 (4 x)$	$∞$
$y = 5 (6 x)$	$∞$
$y = 5 (8 x)$	$∞$

Tab.1. Generatrix and their slope

编号	厚度/mm	斜率	凹凸度
1	3	小	内凹
2	3	中	外凸
3	3	大	直体
4	4	小	外凸
5	4	中	直体
6	4	大	内凹
7	5	小	直体
8	5	中	内凹
9	5	大	外凸

Tab.2. Orthogonal experimental design table

Fig.3. Digital appearance of samples

Fig.4. C⁃shape thin⁃walled structure fabricated by FDM technology

Fig.5. Calculation of Maximum unsupported print angle

Fig.6. Digram of printed structure

Fig.7. Schematic diagram of the overhang angle structure

凹凸性	厚度	斜率	伸长量/ mm	最大应变/mm/mm	最大应力/MPa
1	1	1	101.89	0.125	217.77
1	1	2	118.83	0.122	208.77
1	1	3	74.46	0.131	236.63
1	2	1	46.27	0.083	142.18
1	2	2	52.88	0.081	137.59
1	2	3	33.82	0.086	152.71
1	3	1	24.96	0.059	100.34
1	3	2	29.09	0.058	97.02
1	3	3	18.59	0.061	106.84
2	1	1	49.91	0.262	475.61
2	1	2	43.73	0.31	458.04
2	1	3	58.59	0.22	344.2
2	2	1	23.74	0.111	185.11
2	2	2	20.33	0.13	240.77
2	2	3	27.92	0.173	274.23
2	3	1	13.46	0.054	93.01
2	3	2	11.69	0.074	123.9
2	3	3	15.98	0.084	105.54
3	1	1	114.31	0.207	330.81
3	1	2	130.45	0.206	348.9
3	1	3	79.83	0.207	338.54
3	2	1	54.42	0.142	223.28
3	2	2	61.82	0.156	238.12
3	2	3	40.1	0.166	256.07
3	3	1	30.98	0.11	179.2
3	3	2	33.09	0.112	194.64
3	3	3	22.14	0.134	197.04

Tab.3. Result of FEM

分析主体	方差来源	离差平方和	自由度	均方	F值	P值
位移量	结构	5 589.316	2	2 794.658	14.875	0.001
	厚度	19 329.834	2	9 664.917	51.444	0.001
	斜率	985.946	2	492.973	2.624	0.097
	Residual	3 757.476	2	187.874	1	0.5
最大应力	结构	60 490.452	2	30 245.226	12.001	0.001
	厚度	176 291.483	2	88 145.742	34.974	0.001
	斜率	575.539	2	287.770	0.114	0.893
	Residual	50 406.070	20	2 520.303	1	0.5
最大应变	结构	0.029	2	0.014	13.817	0.001
	厚度	0.062	2	0.031	29.771	0.001
	斜率	0.001	2	0	0.378	0.690
	Residual	0.021	20	0.001	1	0.5

Tab.4. Three ways ANOVA analysis of displacement，maximum stress and maximum strain

结构厚度/m	直体	内凹	外凸
3
4
5

Tab.5. Comparison of top layer stress diagram

Fig.8. Maximum stress heat map

编号	凹凸度	斜率/mm
1	直体	3
2	直体	3
3	直体	3
4	内凹	4
5	内凹	4
6	内凹	4
7	外凸	5
8	外凸	5
9	外凸	5

Tab.6. Table of the numbering structure corresponds

Fig.9. Sample stretching diagram

Fig.10. Fractured samples

Fig.11. Tensile⁃elongation curves of the C⁃shape thin⁃wall structures

样件编号	拉力/N	位移/mm	近似弹性模量/N·mm^-1
ABS⁃T3S1CE	176.8	24.99	7.07
ABS⁃T3S2CX	109	24.99	4.36
ABS⁃T3S3CT	74.2	24.99	2.97
ABS⁃T4S1CX	143	24.99	5.72
ABS⁃T4S2CT	77.4	24.99	3.10
ABS⁃T4S3CE	133.4	24.99	5.34
ABS⁃T5S1CT	130	24.99	5.20
ABS⁃T5S2CE	244	24.99	9.76
ABS⁃T5S3CX	184.6	24.99	7.39
PC⁃T3S1CE	52.8	7.99	6.61
PC⁃T3S2CX	37.4	7.99	4.68
PC⁃T3S3CT	18.6	7.99	2.33
PC⁃T4S1CX	39.2	7.99	4.91
PC⁃T4S2CT	19.8	7.99	2.48
PC⁃T4S3CE	36.8	7.99	4.61
PC⁃T5S1CT	38.6	7.99	4.83
PC⁃T5S2CE	57.2	7.99	7.16
PC⁃T5S3CX	37.2	7.99	4.66

Tab.7. Approximate elastic modulus table of ABS sample

材料	方差来源	离差平方和	自由度	均方	F值	P值
ABS材料	厚度	14.486 865 4	2	7.243 432 698	19.089 345 55	0.049 8
	斜率	0.916 886 251	2	0.458 443 126	1.208 181 204	0.452 9
	凹凸度	19.956 498 89	2	9.978 249 447	26.296 682 75	0.036 6
	误差	0.758 897 96	2	0.379 448 98	1	0.5
PC材料	厚度	3.721 937 918	2	1.860 968 959	52.311 154 6	0.018 8
	斜率	3.797 125 77	2	1.898 562 885	53.367 906 07	0.018 4
	凹凸度	12.731 948 87	2	6.365 974 434	178.945 205 5	0.005 6
	误差	0.071 149 986	2	0.035 574 993	1	0.5

Tab.8. Approximate modulus of elastic modulus ANOVA of ABS material samples

Fig.12. The horizontal plane of the sample

Fig.13. Fracture of samples

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