Analysis of influence factors on impact strength of epoxy/carbon⁃fiber⁃composite⁃molded products

doi:10.19491/j.issn.1001-9278.2024.01.009

Abstract

Abstract:

The influence of molding temperature， molding pressure， holding time， and closing speed on the impact performance of epoxy resin/carbon⁃fiber⁃laminate⁃molded products was investigated through an orthogonal experiment. The of products exhibited significant anisotropy in their impact strength. A range analysis method was used to demonstrate the influence of each factor on the impact performance by an increasing order as follows： holding time>closing speed>molding temperature>molding pressure. The optimal combination of process parameters was determined to be a molding temperature of 130 ℃， a molding pressure of 500 kN， a holding time of 540 s， and a closing speed of 1 mm/s. Compared to the maximum value obtained in the orthogonal experiment， the validation experiment based on this parameter combination for the new products showed an increase in the impact strength by 9.75 %. The microstructure of typical impact fracture samples was analyzed to explore the microscopic mechanism of the influencing factors on the impact performance of the products.

Key words: sheet molding compound, impact performance, process parameter optimization, range analysis, micromorphology

CLC Number:

TQ323.5

RONG Di, JIA Zhixin, LIU Lijun, LI Jiqiang, ZHAO Chuantao, GAO Lizhen, WANG Shaofeng. Analysis of influence factors on impact strength of epoxy/carbon⁃fiber⁃composite⁃molded products[J]. China Plastics, 2024, 38(1): 55-61.

Figures/Tables 20

Fig.1. Epoxy resin/carbon fiber SMC material

Fig.2. Molding system

水平	因素
水平	$T / ℃$	$P / k N$	$t / s$	$v / m m ∙ s - 1$
1	130	400	540	1
2	140	500	600	5
3	150	600	660	10
4	160	700	720	15

水平	因素
水平	$T / ℃$	$P / k N$	$t / s$	$v / m m ∙ s - 1$
1	130	400	540	1
2	140	500	600	5
3	150	600	660	10
4	160	700	720	15

Tab.1. Factor level table of orthogonal test

Fig.3. Sample cutting scheme

试验编号	$T / ℃$	$P / k N$	$t / s$	$v / m m ∙ s - 1$
1	130	400	540	1
2	130	500	600	5
3	130	600	660	10
4	130	700	720	15
5	140	600	720	1
6	140	700	660	5
7	140	700	600	10
8	140	400	540	15
9	150	500	600	1
10	150	700	540	5
11	150	600	720	10
12	150	500	660	15
13	160	400	660	1
14	160	500	720	5
15	160	700	540	10
16	160	600	600	15

试验编号	$T / ℃$	$P / k N$	$t / s$	$v / m m ∙ s - 1$
1	130	400	540	1
2	130	500	600	5
3	130	600	660	10
4	130	700	720	15
5	140	600	720	1
6	140	700	660	5
7	140	700	600	10
8	140	400	540	15
9	150	500	600	1
10	150	700	540	5
11	150	600	720	10
12	150	500	660	15
13	160	400	660	1
14	160	500	720	5
15	160	700	540	10
16	160	600	600	15

Tab.2. Orthogonal test parameters

试验编号	$a c U ¯ (X) / k J ∙ m - 2$	$σ X$	$a c U ¯ (Y) / k J ∙ m - 2$	$σ Y$
1	50.85	12.93	67.80	15.75
2	45.85	11.84	57.75	9.39
3	42.27	4.35	49.48	5.40
4	49.10	8.97	46.53	4.75
5	49.50	5.75	54.51	11.42
6	47.96	4.06	33.82	10.76
7	38.07	3.13	46.47	9.82
8	37.19	12.62	56.04	5.56
9	42.71	1.91	66.56	9.99
10	43.03	4.76	52.09	3.49
11	37.58	8.46	51.43	12.81
12	41.95	6.54	45.39	17.25
13	41.34	13.25	48.77	9.48
14	43.44	4.80	50.29	8.64
15	41.39	4.97	54.72	6.40
16	48.47	6.04	48.04	6.71

试验编号	$a c U ¯ (X) / k J ∙ m - 2$	$σ X$	$a c U ¯ (Y) / k J ∙ m - 2$	$σ Y$
1	50.85	12.93	67.80	15.75
2	45.85	11.84	57.75	9.39
3	42.27	4.35	49.48	5.40
4	49.10	8.97	46.53	4.75
5	49.50	5.75	54.51	11.42
6	47.96	4.06	33.82	10.76
7	38.07	3.13	46.47	9.82
8	37.19	12.62	56.04	5.56
9	42.71	1.91	66.56	9.99
10	43.03	4.76	52.09	3.49
11	37.58	8.46	51.43	12.81
12	41.95	6.54	45.39	17.25
13	41.34	13.25	48.77	9.48
14	43.44	4.80	50.29	8.64
15	41.39	4.97	54.72	6.40
16	48.47	6.04	48.04	6.71

Tab.3. Result of impact strength for the Orthogonal test parameters

Fig.4. Impact properties of the products in different sampling directions

Mann⁃Whitney U

Wilcoxon W

渐进显著性

（双尾）

精确显著性

［2*（单尾显著性）］

X试样冲击强度均值

（16组全部试样） $a c U$ /MPa

Y试样冲击强度均值

（16组全部试样） $a c U$ /MPa

≤

0.05

≤

0.001

43.79

51.86

Mann⁃Whitney U

Wilcoxon W

渐进显著性

（双尾）

精确显著性

［2*（单尾显著性）］

X试样冲击强度均值

（16组全部试样） $a c U$ /MPa

Y试样冲击强度均值

（16组全部试样） $a c U$ /MPa

42.000

178.000

-3.241

0.001

≤

0.05

≤

0.001

43.79

51.86

Tab.4. Mann⁃Whitney U test for impact strength of patterns in different sampling directions

Fig.5. Metallographic microscope images of typical patterns in different sampling directions

各水平冲击强度均值 $a c U$ /MPa	影响因素
各水平冲击强度均值 $a c U$ /MPa	$T$	$P$	$t$	$v$
$k 1$	55.39	52.49	57.66	59.41
$k 2$	47.71	53.50	54.71	48.49
$k 3$	53.87	51.03	44.37	50.52
$k 4$	50.46	50.41	50.69	49.00
$R$	7.68	3.09	13.29	10.92

各水平冲击强度均值 $a c U$ /MPa	影响因素
各水平冲击强度均值 $a c U$ /MPa	$T$	$P$	$t$	$v$
$k 1$	55.39	52.49	57.66	59.41
$k 2$	47.71	53.50	54.71	48.49
$k 3$	53.87	51.03	44.37	50.52
$k 4$	50.46	50.41	50.69	49.00
$R$	7.68	3.09	13.29	10.92

Tab.5. Impact strength range analysis results

Fig.6. Statistical chart of the range analysis of the influence of molding parameters on the impact strength of products

正交试验中冲击

强度最大值 $a c U$ /MPa

最优参数组制品Y方向试样

冲击强度平均值 $a c U$ /MPa

冲击强度

提高百分比/%

67.80

74.41

9.75

正交试验中冲击

强度最大值 $a c U$ /MPa

最优参数组制品Y方向试样

冲击强度平均值 $a c U$ /MPa

冲击强度

提高百分比/%

67.80

74.41

9.75

Tab.6. Impact strength of the sample before and after optimization of molding parameters

Fig.7. Relationship between molding temperature and impact strength

Fig.8. Metallographic microscope images of the products at different molding temperature

Fig.9. Relationship between impact strength and molding pressure

Fig.10. Metallographic microscope images of the products under different molding pressure

Fig.11. The relationship between impact strength and pressure holding time

Fig.12. SEM of the products under different pressure holding time

Fig.13. Relationship between impact strength and die closing velocity

Fig.14. Metallographic microscope images of the products at different closing speed

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