Experimental research was conducted on the relationship between the graphitic crystallite in the ablation glass fiber reinforced epoxy composite and the microwave transmission decay at a frequency of 10GHz. Ablation samples were prepared by intense laser irradiation of 100W •cm-2 for different time. The microstructure and component of the ablation samples were characterized by means of X-ray diffraction and Raman spectra. The electromagnetic characteristics were investigated by vector network analyzer at 10GHz. When laser of 100W•cm-2 irradiated the samples shorter than8seconds, the microwave transmission decay remained small. When the laser irradiated the samples 8 seconds, the graphitic crystallites were detected and the microwave transmission decay escalated. With increasing irradiation time, the size and quantity of graphitic crystallites , as well as the microwave transmission decay increased. In brief, we concluded that the generation of graphitic microcrystallites induced by laser irradiation attributed to the microwave transmission decay.
The purpose of this investigation is to study laser ablation properties of glass fiber composite under obliquely impinging air jet. The continue wave near infrared laser ablation of fiber-reinforced composite materials under air jet with different velocity and inclination was studied experimental. The laser intensity is uniform distribution and the weight of sample was measured before and after experiment. Effective ablation heat was defined as the ratio of laser energy to weight loss. The experimental results showed that the process of the glass fiber reinforced epoxy composite ablation under laser and air jet can be divided into two stages. The first stage is mainly thermal ablation. The effective ablation heat increased as the inclination angle increased under same laser intensity. The effective ablation heat decreased with laser irradiation duration under same inclination angel and laser intensity. the second stage is mainly mechanical damage. the remain materials was broken and removed by air jet impingement, thus the effective ablation heat decreased evidently.
Kevlar/nomex honeycomb sandwich structures are widely used by many apparatuses and vehicles in many domains. Since there are large quantities of epoxy resins in the structure, it is considerable to study the process that the structure is heated and produces pyrolysis gases which diffuse among the honeycomb. In this paper, the process of a laser beam irradiating a kevlar/nomex honeycomb sandwich is studied for building a mathematical model. The process is divided into two parts. One part focuses on the pyrolysis gas producing, the other one focuses on the gas diffusing among the honeycomb. The pyrolysis gas producing model is built according to experiment analysis, as a Boltzmann formula. The gas diffusion model is also built in the form of ODE equations. Validation experiment is carried out, demonstrating the model correct and accurate. Finally, the two models are combined together. By comparing with experiment, the laser irradiating and pyrolysis gas diffusing model is demonstrated to be appropriate to the case that kevlar laminas are bonded to the nomex honeycomb.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.