| The earth penetrating weapons(EPW) can destroy the underground multi-layer targets just ensuring the ballistic security and operation credibility. Fuze assembled on projectile,as the command center,can maximize the damage performance of EPW when it works.So the main purpose is to insure the fuze working normally during the penetration.The projectile is subjected to severe loads over a short duration,accompanied by high temperature,huge pressure and stress wave propagation during the penetration,the harsh environment can result in high-g and millisecond-scale pulse-width load on fuze in projectile,and negative effects on stability of electronic circuits and reliability of mechanical structures in fuze.Thus,technology of anti-overload of fuze is always worldwide concerning at the first appearance of penetration fuze.Vibration isolation,potting protection,electronic circuit design and reinforcement are proved to be main protection measures for fuze.Numerical simulation is the basic reference for protection improvements as a result of the large-scale high fees and manpower. Otherwise,theoretical method can simply analyze the fuze protection by vibration and stress wave theories on the condition of model components’idealization.Theoretical results can provide direction to protection optimization of fuze.In the first part of this thesis,propagation law of stress wave in potting layer and potting material parameters’effect on stress wave attenuation are obtained.On account of the limitation of single-degree-of-freedom mass-spring system,potting layer in fuze is simplified in thickness direction to be one-degree analysis model.Viscoelastic material model whose characteristics resemble high polymer potting material is chosen.Difference maked by density,elastic module and relaxation time at high strain rate on stress wave attenuation in potting layer is investigated by characteristic numerical difference method,which provides theoretical basis for potting thickness design.This conclusion will be used again in the next part.In the second part of this thesis,based on the first part,stress wave attenuation through external shell,potting layer and electronic component is presented,as well as the influences of potting material parameters(density,elastic module and relaxation time at high strain rate) on this process,which can give a favor for potting layer design. Stress wave has reflection and transmittion phenomena at the interface of external shell and potting layer,potting layer and electronic component as well.Concerning stress wave attenuation in potting layer concluded in first part and the interface phenomena,the relationship between potting material parameters and stress arrived at electronic component is illustrated,which offers a way to optimizing potting design.One design of potting layer besmeared multi-thin layers is proved theoretically to reduce the stress response on electronic component.In the third part of this thesis,numerical simulation software is used to reproduce the prcess of projectile penetrating target,achieve dynamic response of electronic components in fuze,and validate theoretical results in the former two parts.Simulation analysis consists of two steps,firstly,overloading response of simplified projectile is simulated during penetration,then,particular projectile with electronic components will be subjected to the overload from first step,dynamic responses of electronic components like stress,strain and acceleration can be obtained,and distribution results of stress,strain and acceleration can give an advice to mechanical structure design of fuze.On the other hand, responses of electronic components after changing potting material parameters are compared with original results,which is consistent with theoretical expectation.This part enhances the reliability of former theoretical conclusions on potting design optimization,and makes theoretical conclusions valuable in engineering application of impact resistence protection of fuze. |
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