瓦楞型竹束单板复合材料的制备及力学性能表征

Preparation and mechanical properties of corrugated bamboo bundle laminated composites

探索了一种新型竹质工程构件——瓦楞型竹束单板复合材料(CBLC)的制备工艺,研究了三种典型铺装类型(Ⅰ型:(0°)6;Ⅱ型:(0°/90°)3;Ⅲ型:(90°)6)对其拉伸、双向弯曲、三维压缩性能的影响,同时利用数字散斑相关方法(DSCM)对其弯曲应变场信息进行了表征。结果表明:铺装类型对各项力学性能有明显影响,对于拉伸、纵向弯曲性能,Ⅰ型>Ⅱ型>Ⅲ型,对于横向弯曲,Ⅱ型>Ⅲ型>Ⅰ型。不同铺装类型下CBLC的拉伸断裂机制亦各不相同:Ⅰ型为延性断裂,Ⅱ型为逐渐分层断裂,Ⅲ型为脆性断裂。x和y方向应变场集中分布在试样底端最外层瓦楞波形连接处,且Exx<Eyy。多重比较分析表明:抗压缩性能在三维方向上存在明显差异,且y>x>z;铺装类型对CBLC的抗压载荷、抗压强度有很大影响,而抗压模量差异不明显。

A novel bamboo bundle laminated composite（CBLC） with a corrugated structure was developed. Three types of stacking sequences including type Ⅰ （0°）6, typeⅡ（0/90°）3 and type Ⅲ（90）6 were designed. The effect of stacking sequence on the properties of tension, biaxial bending and 3D compression were investigated, meanwhile, the strain fields under bending load were characterized by digital spackle correlation method （DSCM）. It has been found that the behaviors of tension, bending and compression are effected significantly by stacking sequence of composites with type Ⅰ 〉 type Ⅱ 〉 type In for the stretching and vertical bending tests, and type Ⅱ 〉 type Ⅲ 〉 type I for the lateral bending performance. The fracture mechanisms under tensile process are dissimilar, which are controlled by stacking sequences. Type I shows a ductile fracture model, type Ⅱdisplays a gradual delamination and type Ⅲ illustrates a brittle failure. Strain fields in ：r and y direction mainly concentrate at the outermost layer near the bottom of corrugated wave connection with Exx〈Eyy. Multiple comparisons show that the compressive properties of CBLC are significantly different in the three dimensions with y〉x〉z. The stacking sequences have a significant effect on the compression loading and strength, except for compression modulus.