馬治軍，黃朝陽，滕昊，林建平

復合材料成形

鋼?CFRP異質(zhì)復合B柱的彎曲實驗分析

馬治軍1，黃朝陽1，滕昊2，林建平2

（1.上海賽科利汽車模具技術應用有限公司，上海 202106；2.同濟大學 機械與能源工程學院，上海 200092）

為提高B柱的抗彎性能，通常會在B柱上額外焊接補丁板，但同時也增加了B柱的重量。在原始B柱上鋪設碳纖維增強復合材料（CFRP），獲得鋼?CFRP異質(zhì)復合B柱，取消B柱的鋼制加強板，實現(xiàn)B柱的輕量化。通過熱沖壓制備原始B柱及帶補丁板B柱，并以原始B柱為凹模，采用真空袋壓工藝制備鋼?CFRP異質(zhì)復合B柱?；?018版C?NCAP側(cè)面碰撞實驗要求，設計B柱三點彎曲夾具，進行原始B柱、帶補丁板B柱及鋼?CFRP異質(zhì)復合B柱的三點彎曲實驗，并對其重量及彎曲性能進行分析。原始B柱重量4.1 kg，三點彎曲實驗測得其剛度為0.763 kN/mm，最大載荷為21.59 kN，平均力為14.52 kN；帶補丁板B柱質(zhì)量為5.6 kg，三點彎曲實驗測得其剛度為1.095 kN/mm，最大載荷為31.08 kN，平均力為18.38 kN；鋼?CFRP異質(zhì)復合B柱總質(zhì)量4.7 kg，三點彎曲試驗測得其剛度為1.071 kN/mm，最大載荷為31.76 kN，平均力為19.58 kN。在保持剛度、最大載荷及平均力等彎曲力學性能不變的前提下，相對于帶補丁板B柱，鋼?CFRP異質(zhì)復合B柱可以減輕質(zhì)量0.9 kg，并且吸能更優(yōu)，實現(xiàn)了B柱的輕量化。

碳纖維增強復合材料；真空袋壓工藝；鋼?CFRP異質(zhì)復合B柱；三點彎曲；輕量化

金屬-碳纖維增強復合材料（Carbon Fiber Reinforced Plastic，CFRP）異質(zhì)復合構(gòu)件將金屬與CFRP連接后一起進行承載，可提高構(gòu)件的拉伸、彎曲、抗沖擊等力學性能[1-5]，進而助力實現(xiàn)零件的輕量化設計。根據(jù)金屬和CFRP成形先后順序及連接方式，目前金屬-CFRP異質(zhì)復合結(jié)構(gòu)成形工藝路線可以分為4類：金屬和CFRP分別制造成形后，再采用膠、鉚、焊等手段進行連接[6-9]；金屬零件成形后，以金屬零件為模，同時進行CFRP成形及金屬和CFRP的連接[10-11]；金屬和CFRP同步成形并實現(xiàn)連接[12-13]；先將金屬和CFRP采用熱壓或熱壓罐成形等工藝制備成金屬?CFRP異質(zhì)復合板，再采用其他成形工藝制備為需要的形狀[14-17]。

金屬-FRP異質(zhì)構(gòu)件被廣泛應用于航空領域及汽車領域，如機翼、機身蒙皮、車身等[18-21]。2015年，寶馬公司首先在其7系車上應用了金屬-CFRP異質(zhì)復合構(gòu)件，如車頂橫梁、B柱、C柱、門檻梁及中央通道上，使整車重量減輕了130 kg[22]。陸冉[23]基于成形加膠接的成形工藝制造了鋼-CFRP異質(zhì)復合B柱，對制造的CFRP B柱補丁板進行了三點彎曲仿真與實驗，在剛度不變情況下，實現(xiàn)了補丁板質(zhì)量減輕31%。熊長麗[24]先采用單向碳纖維布和樹脂傳遞模塑工藝制造了CFRP補丁板，再將補丁板和鋼質(zhì)B柱膠粘在一起，在總剛度不變的情況下，補丁板減重70%。

文中以某汽車帶補丁板B柱為研究對象，在保持剛度、強度、平均力等指標不變的情況下，以鋼制B柱構(gòu)件為模，制作了鋼-CFRP異質(zhì)復合B柱，并通過三點彎曲實驗與分析，為鋼-CFRP異質(zhì)復合B柱的應用提供技術參考。

1 鋼-CFRP異質(zhì)復合B柱的成形工藝與三點彎曲實驗

1.1 鋼-CFRP異質(zhì)復合B柱的真空袋壓成形制造

本研究中的鋼-CFRP異質(zhì)復合B柱是在已經(jīng)成形的原始B柱上鋪設碳纖維增強復合材料，采用真空袋壓工藝制成。具體成形制造工藝流程：采用熱沖壓成形工藝制備原始B柱；對鋼板進行表面處理，主要目的是提高鋼與CFRP之間的結(jié)合性能，故對鋼板表面進行噴砂處理；在原加強板位置鋪設復合材料預浸料，共鋪設5層12K雙向預浸料，其單向拉伸強度為983 MPa；將鋪設好CFRP預浸料的B柱依次用隔離膜、透氣氈、真空袋等進行包裹；將真空袋打包好的鋼-CFRP異質(zhì)復合B柱放進熱壓罐中，并通過真空快速接頭與真空泵連接，固化成形，完成鋼- CFRP異質(zhì)復合B柱的制作。

1.2 鋼-CFRP異質(zhì)復合B柱三點彎曲實驗

根據(jù)2018版C-NCAP側(cè)面碰撞實驗要求[25]，研究設計了三點彎曲夾具。其中，沖頭半徑為125 mm，2個支撐腳架半徑為10 mm，如圖1所示。B柱根據(jù)側(cè)面碰撞實驗中沖擊位置放置于2個支撐上，三點彎曲實驗在MTS萬能實驗機上進行，沖頭下壓速率為15 mm/min。實驗在室溫下共進行3組，分別是原始B柱（無補丁板）、帶補丁板B柱及鋼-CFRP異質(zhì)復合B柱。以沖頭與B柱接觸開始的時刻為實驗起始點，沖頭下壓80 mm時實驗停止。

圖1 B柱三點彎曲實驗

2 鋼-CFRP異質(zhì)復合B柱三點彎曲實驗結(jié)果與分析

在MTS萬能實驗機上獲得B柱三點彎曲實驗的載荷-位移曲線，如圖2所示，各個B柱的失效形式如圖3所示，可見原始B柱（無補丁板）的失效形式為壓潰失效；帶補丁板的B柱主要失效形式為補丁板焊點失效之后的壓潰失效；鋼-CFRP異質(zhì)復合B柱沒有出現(xiàn)整體CFRP脫粘的現(xiàn)象，主要的失效形式為中間位置CFRP的斷裂及斷裂處附近界面脫粘，表明真空袋壓工藝可以較好實現(xiàn)CFRP的成形與鋼?CFRP界面的連接。

圖2 B柱三點彎曲實驗的載荷-位移曲線

由圖2可知，當沖頭位移小于9.8 mm時，原始B柱和鋼-CFRP異質(zhì)復合B柱的承載小于帶補丁板B柱；當沖頭加載到14.5 mm左右時，鋼-CFRP異質(zhì)復合B柱的載荷已經(jīng)達到了補丁板B柱的強度；當沖頭加載到16.9 mm時，由于發(fā)生了焊點失效，補丁板B柱載荷出現(xiàn)突然下降，隨著載荷增大，越來越多焊點出現(xiàn)失效；鋼-CFRP異質(zhì)復合B柱在沖頭分別加載到20.2 mm時，CFRP開始斷裂，載荷出現(xiàn)突然下降；原始B柱、帶補丁板B柱和鋼?CFRP異質(zhì)復合B柱分別在沖頭加載到34.5、33.8、40.1 mm處時載荷達到峰值。此外，鋼?CFRP異質(zhì)復合B柱達到峰值后，其對抗侵入量與吸能效應明顯優(yōu)于帶補丁板B柱。

所有B柱的剛度、最大載荷、平均力的具體數(shù)值如表1和圖4所示。通過補丁板和CFRP對鋼板進行補強，均可提高B柱的剛度、最大載荷、平均力等指標，但兩者增強方式存在一定區(qū)別。鋼-CFRP異質(zhì)復合B柱質(zhì)量相對于帶補丁板B柱減少了0.9 kg，剛度、最大載荷、平均力分別達到了帶補丁板B柱的98%、102%、107%，表明鋼-CFRP異質(zhì)復合B柱吸能效果優(yōu)于帶補丁板B柱，實現(xiàn)了B柱的輕量化設計。

圖3 B柱失效圖

表1 B柱力學性能對比

Tab.1 Comparison of mechanical properties of B-pillar

圖4 B柱力學性能對比

3 結(jié)論

通過CFRP替代鋼制補丁板，實現(xiàn)了B柱輕量化設計。基于2018版C-NCAP側(cè)面碰撞實驗要求設計了B柱三點彎曲夾具，并進行了原始B柱、帶補丁板B柱及鋼?CFRP異質(zhì)復合B柱的三點彎曲實驗，通過對比各個B柱的質(zhì)量、剛度、最大載荷、平均力，可以得出以下主要結(jié)論。

1）通過真空袋壓工藝可較好地同時實現(xiàn)CFRP成形與鋼-CFRP的界面連接。

2）在保持剛度、最大載荷及平均力等彎曲力學性能不變的前提下，鋼-CFRP異質(zhì)復合B柱相對帶補丁板B柱可以減輕質(zhì)量0.9 kg，實現(xiàn)B柱的輕量化。

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Bending Test Analysis of Steel-CFRP Hybrid Composite B-Pillar

MA Zhi-jun1, HUANG Zhao-yang1, TENG Hao2, LIN Jian-ping2

(1. Shanghai Superior Die Technology Co., Ltd., Shanghai 202106, China; 2. College of Mechanical Engineering, Tongji University, Shanghai 200092, China)

In order to improve the bending resistance of B-pillar, additional patch plates are usually welded to the B-pillar, which increases the weight of the B-pillar at the same time. The work aims to lay carbon fiber reinforced composite (CFRP) on the original B-pillar to obtain the steel-CFRP hybrid composite B-pillar, and eliminate the steel reinforced plate to realize the lightweight of B-pillar.The original B-pillar and B-pillar with patch plate were prepared by hot stamping. The steel-CFRP hybrid composite B-pillar was fabricated by vacuum bag pressure molding with the original B-pillar as the die. Based on the requirements of C-NCAP side impact test (2018 Edition), a three-point bending fixture for B-pillar was designed, and three-point bending test was carried out to original B-pillar, B-pillar with patch plate and steel-CFRP hybrid composite B-pillar. The original B-pillar had the weight of 4.1 kg, stiffness of 0.763 kN/mm measured by three-point bending test, maximum load of 21.59 kN and average force of 14.52 kN. The B-pillar with patch plate had the weight of 5.6 kg, stiffness of 1.095 kN/mm measured by three-point bending test, maximum load of 31.08 kN and average force of 18.38 kN. The steel-CFRP hybrid composite B-pillar had the total weight of 4.7 kg, stiffness of 1.071 kN/mm measured by three-point bending test, maximum load of 31.76 kN and average force of 19.58 kN. Under the premise of maintaining the bending mechanical properties such as stiffness, maximum load and average force, the weight of steel-CFRP hybrid B-pillar can be reduced by 0.9 kg compared with that of B-pillar with patch plate, and the energy absorption is better, which realizes the lightweight design of B-pillar.

carbon fiber reinforced plastic; vacuum bag pressure molding; steel-CFRP hybrid composite B-pillar; three-point bending; lightweight

10.3969/j.issn.1674-6457.2023.01.013

TD406

A

1674-6457(2023)01-0101-05

2022?01?17

2022-01-17

馬治軍（1988—），男，博士，主要研究方向為熱成形鋼工藝及其輕量化。

MA Zhi-jun (1988-), Male, Doctor, Research focus: hot forming steel process and its lightweight.

滕昊（1996—），男，博士研究生，主要研究方向為鋼?CFRP異質(zhì)復合構(gòu)件力學性能及界面結(jié)合性能。

TENG Hao (1996-), Male, Doctoral candidate, Research focus: mechanical properties and interface bonding properties of steel-CFRP hybrid composite structures.

馬治軍, 黃朝陽, 滕昊, 等. 鋼?CFRP異質(zhì)復合B柱的彎曲實驗分析[J]. 精密成形工程, 2023, 15(1): 101-105.

MA Zhi-jun, HUANG Zhao-yang, TENG Hao, et al. Bending Test Analysis of Steel-CFRP Hybrid Composite B-Pillar[J]. Journal of Netshape Forming Engineering, 2023, 15(1): 101-105.