Stdudy On Damage Tolerant Of Honeycomb Sandwich Structure With Metal Skins

Honeycomb sandwich structure with metal skins and Nomex honeycomb core is a lightweight and high-strength material.It has been widely used in Aerospace area.Although it has the significant superiority,it has some weaknesses:Honeycomb sandwich panels will get damage in skin and honeycomb core after low-energy impact,which will reduce the mechanical proterty,and this kind of damage can not be found easily;The mechanical property of Nomex honeycomb core will decrease obviously in hydrothermal conditions;During the process of production and service period,sandwich panels may debond between the skin and honeycomb.So,it is important to evaluate the mechanical property of damaged honeycomb sandwich structure with metal skins and Nomex honeycomb core in certain environment conditions.This paper investigates the relationship between the impact energy and indent depth;growth characteristic of fatigue and residual strength of honeycomb sandwich structure by experimental method,which provide indispensable test data for tolerant analysis of this structure.the relationship between impact energy and indent depth was found with an automatic drop-weight impact machine,and determine the corresponding impact energy of the barely visible impact damage(BVID)and the clearly visible impact damage(CVID)regarding to the different samples with various thickness skin with the residual strength after impact.Validated samples have no-growth characteristics of damaged with four point blending fatigue test.Using four point blending static test get residual static blending strength and damage mode of impacted damage samples and skin-stiffener debond samples after hygrothermal aging or fatigue loading,and get the content of residual strength reduce compared with the non-damage simples in room temperature,and analyze the influence of various factors affect the residual strength.At last,we computed the sample's blending strength test by using the finite element software ANSYS,and get the characteristic value and sample's deformation when buckling.