Delamination failure analysis of G10 insulator in electromagnetic rail launcher

The electromagnetic(EM)rail launcher G10 insulator is prone to delamination damage during launch,which affects the service life of the insulator.Through the secondary development of ABAQUS®commercial finite‐element software,an EM‐structure coupling launch dynamics model considering projectile‐barrel coupling is established.The simulation indicates that the transverse swing of the projectile changes in a sine‐like law,and the time of the upper half wave corresponds to the pulse width of the impact force pulse waveform.The stress concentration occurs on the inner surface of the insulator where the contact‐impact occurs,resulting in impact damage.The midline of the insulator inner surface bears a large compressive strain under the action of pre‐tightening force,and the insulator is compressed oscillatingly under the influence of the timevarying load of the rail during launch.Under the condition of repeated launch,the launch package repeatedly impacts the insulator,and the alternating load of the rail is cyclically loaded on the insulator with impact damage,which will cause the compression fatigue of the insulator and the expansion of impact damage crack.They are the main reasons for the delamination failure of insulator,and the experimental analysis is carried out.This study provides a method to study the delamination failure mechanism of the insulator,and provides guidance for improving the life of the insulator.

Beagle Dogs Have Low Susceptibility to Florida Clade 2 H3N8 Equine Avian Influenza

Dear Editor,Dogs were long considered refractory to influenza viruses until the equine-origin H3N8 canine influenza virus(CIV)was first isolated in the United States of America(U.S.A)in 2004(Crawford et al.2005).Since then,H3N8 CIV of equine-origin strains has been circulating in dogs in the U.S.A.In 2006,another CIV of avian origin H3N2 subtype was isolated from dogs in China(Li et al.2010).Recently,H3N2 CIV strains have become endemic in dog populations in China,South Korea,and North America(Borland et al.2020).