Research On Monitoringof Manufacturing And Low Energy Impact Damage Propertyof Cfrp Withfbg Sensors

Carbon fiber reinforced plastics (CFRP) have been widely used in the aerospace, transportation, construction, sporting goods and other application areasfor their light weight, high strength, easy to shape, can be designed and other advantages. However, due to the weak layer performance of inter-composite laminate structure, as well as a significant anisotropy, they are prone to delamination when subjected to external shocks, thereby causing material degradation and the materials will be under serious security risks. Such damage can not be observed from the outside, and are difficult to make predictions. To solve this problem, an effective means of monitoring is particularly important.Fiber Bragg grating (FBG)sensor is an efficient monitoring instruments which has a rapid development in recent years. It has lots of advantages such as small size, high precise monitoring, good response, anti-electromagnetic interference, anti-radio interference ability and other excellent performance. It’s suitable for real time nondestructive monitoring of carbon fiber composites.Based on FBG sensor characteristics, this paper studied the FBG sensing mechanism and verify its temperature and strain sensitivity firstly. Then embedded the FBG in CFRPwhich using vacuum assisted resin infusion process (VARI).After testing, the FBG and the CFRP laminate have good compatibility, and embedded FBG in the interior of the laminate still have good detection sensitivity.After a series of tests, It is proved that FBG sensor can accurately reflect the changes of the internal stress and the temperature of compositeduring curing, and it can also accurately capture the gel time.The wavelength drift characterization of after curingcan reflect the residual stresses which enablereal-time monitoring and process adjustment in time.In order to study the effects of low energy impact to CFRP using FBG sensors,this paper studied the failure mechanism of composite laminatesandtake impact energy, impact times buried away, buried azimuth as variables to consider the impact damage.Experimental results show that FBG sensors can monitor the impactwhich follow the impact theory. And this means of monitoring can be more sensitivity and accuracy as a kind of non-destructive testing.The wavelength peaks can reflect the impact energy while the fluctuations differences can reflect thematerial damage suffered in the internal situation.That is to saychanges of wavelength of the FBGsensors can reflect the degree of damage in composite laminates.The FBG can still maintain good monitoring results in the case of multiple impacts. Then the influence of the layout position of FBG sensors have been studied, theconclusions can been summarized that the closer to the point of impact, the better the monitoring is. So we should takeboth monitor effects and layout costs into account inorder to optimize layout distancein practice.On this basis, this paper laid several FBG sensors in different locations to monitor thelow energy impact of the composite simultaneously, and presents the feasibility of locating the composite impact damagebased on FBG sensors.