竹复合管材湿热老化性能及其机理

采用加速老化试验方法对竹复合管材的湿热老化性能及老化机理进行研究，探究不同湿热老化历时下竹复合管材拉伸、压缩和弯曲性能的变化。结果表明，在交变湿热应力作用下，竹复合管材拉伸强度、压缩强度、压缩弹性模量、弯曲强度和弯曲弹性模量随湿热老化时间延长呈幂指数降低，拉伸劣化大于弯曲，弯曲劣化大于压缩，模量劣化大于强度；湿热老化28次后，竹复合管材拉伸强度、压缩强度、压缩弹性模量、弯曲强度和弯曲弹性模量分别降低34.11%、25.64%、26.39%、26.14%和27.83%。交变湿热应力使结构层树脂和竹纤维均发生湿胀，结构层树脂湿胀率小于竹纤维，不均匀的湿胀使结构层树脂受拉、竹纤维受压，结构层树脂竹纤维界面产生剪切力，树脂开裂、脱落，纤维树脂界面形成孔洞和微裂纹降低有效应力传递，当剪切力大于界面粘结力时，界面损伤模式主要表现为脱粘以及剪切分层。

Hygrothermal Aging Property of Bamboo Composites Pipe and Its Mechanism

The hygrothermal aging properties and aging mechanism of bamboo composites pipe are studied using accelerated aging test method to study the change in its tensile, compressive and flexural properties under different hygrothermal aging duration. The results show that the tensile strength, compressive strength, compressive modulus of elasticity, flexural strength and flexural modulus of elasticity of bamboo composite pipe decrease exponentially with the aging time, presenting greater deterioration of tensile than flexural, greater deterioration of flexural than compressive, and greater deterioration of modulus than strength. The tensile strength, compressive strength, compressive modulus, flexural strength and flexural modulus decrease by 34.11%, 25.64%, 26.39%, 26.14% and 27.83%, respectively after 28 times hygrothermal aging. The resin and bamboo fiber are both wet swelling under alternating hygrothermal stress. The wet swelling rate of resin is less than that of bamboo fiber, and uneven wet swelling makes the resin pulled and bamboo fiber pressured, leading to shear force at the interface of resin and bamboo fiber. As a result, the resin cracks and falls off, and pores and microcracks are formed at the interface between fiber and resin, which reduces effective stress transfer. When the shear force is larger than the interfacial bonding force, debonding and shear delamination are the failure modes of the interface.