方舱侧板用碳纤维增强杨桉复合板的研制

Preparation of carbon fiber reinforced poplar eucalyptus composites for shelter side panels

为开发一种用于方舱的轻质高强木质结构复合材,制备了杨桉复合板对照组(A)、碳纤维表层横向增强杨桉复合板(B)、碳纤维表层纵向增强杨桉复合板(C)、碳纤维表层双层纵横对称增强杨桉复合板(D)共4种杨桉复合板结构,测试了4种结构的密度、静曲强度和弹性模量、水平剪切强度、24 h吸水率、24 h吸水厚度膨胀率和握螺钉力,探究了碳纤维不同增强方式对杨桉复合板物理力学性能的影响。结果表明:经碳纤维增强后,D组的密度增加幅度最大,增加了13.9%,干态下杨桉复合板的横向水平剪切强度都有所增强,D组增加幅度最大,增加了42.5%。24 h增湿后横向水平剪切强度降低,D组降低幅度最小,降低了4.7%。D组的吸水率下降49.5%,吸水厚度膨胀率下降71.6%。经过表面碳纤维增强后板面握螺钉力明显提高,D组提高幅度最大,提高了51.6%。根据SJ 20500—1995《方舱大板通用规范》,方舱材料的静曲强度一般大于25 MPa,对照组A的纵向静曲强度大于25 MPa,横向静曲强度小于25 MPa,不满足方舱材料的静曲强度要求,经碳纤维增强后,B、C、D组纵、横静曲强度均大于25 MPa,可以满足方舱侧板材料的静曲强度要求,其中碳纤维表层双层纵横增强对杨桉复合板的增强最为明显。

In order to develop lightweight and high-strength wood structural composites for shelters, the control group(A), the transverse reinforcement of carbon fiber(CF) group(B), the longitudinal reinforcement of CF group(C) and the two-layer longitudinal and transverse symmetrical reinforcement of CF group(D) were studied. Transverse reinforcement meant that the direction of carbon fiber was perpendicular to the grain direction of the surface poplar veneer, and longitudinal reinforcement meant that the direction of carbon fiber was parallel to the grain direction of the surface poplar veneer. The density, modulus of rupture and modulus of elastic, horizontal shear strength, 24-h water absorption, 24-h water absorption thickness swelling rate and nail-holding force of the four structures were measured. The results showed that, after being reinforced with carbon fibers, the density of Group D increased by 13.9%. The longitudinal and horizontal static curvature strengths of Group D met the standards of shelter materials, and the horizontal shear strength of the vertical core board in the dry state was enhanced, the increase range of the horizontal shear strength in Group D was the largest, which had an increase range of 42.5%. After 24-h humidification, the horizontal shear strength decreased in varying degrees. Group D had the smallest decrease, and the decline was 4.7%. For Group D, the water absorption decreased by 49.5% and the water absorption thickness swelling decreased by 71.6%. After the surface carbon fiber reinforcement, the nail-holding force on the plate surface was enhanced and the maximum increase in Group D was 51.6%. The edges of the four groups were vertical core structure, and the carbon fiber only strengthened the plate surface, not the plate edges. Therefore, the nail-holding force of the four groups had no obvious change. According to SJ 20500-1995 General specification for sandwich panels of shelters, the modulus of rupture of shelter materials is generally greater than 25 MPa, while the longitudinal strength of control Group A was greater than 25 MPa and the transverse modulus of rupture was smaller than 25 MPa, which did not meet the requirements of the modulus of rupture of shelter materials. The longitudinal and transverse modulus of rupture of Groups B, C and D were all greater than 25 MPa, which met the requirements of the modulus of rupture of the side panel material of the shelter. The enhancements of the longitudinal and transverse strengths of the carbon fiber surface layer were the most obvious.