The invention discloses a starlike negative Poisson's ratio structure based on dielectric electroactive polymers. The structure is formed by a starlike negative Poisson's ratio cell array, and the cells consist of a quadrangular starlike bone 101 and four tendons (102~105). The tendons are made of dielectric electroactive polymers, and are of a sandwich structure, sandwich materials are dielectric elastomers, two sides are flexible electrodes, and the Young's modulus of the bone is larger than that of tendon materials. The flexible electrodes of two sides of the tendons are connected with the positive electrode and the negative electrode of high voltage direct current power supplies 106~109, and the voltage and path open-circuit state are adjustable. The starlike negative Poisson's ratio cells are arrayed, and thus the starlike negative Poisson's ratio structure can be formed. Since the mechanical states and electrostatic states of the dielectric electroactive polymers are mutually coupled, mutual conversion between mechanical energy and electric energy can be realized, and functions of structure real-time variability, actuation, energy recovery and sensing of the starlike negative Poisson's ratio structure are realized.

Starlike negative Poisson's ratio structure based on dielectric electroactive polymers

The invention discloses a novel configuration honeycomb sandwich panel composed of an aluminum alloy panel, a honeycomb core layer, a composite material panel and a sandwich panel body. The honeycombsandwich panel body is formed by pressing and sequentially includes the aluminum alloy panel, the honeycomb core layer and the composite material panel. The surface of the aluminum alloy panel is connected with the top of the honeycomb core layer, the inner surface of the composite material panel is connected with the bottom of the honeycomb core layer, a plurality of honeycomb unit cells are equidistantly and parallelly arranged and glued on a large rib plate, line contact parts between the honeycomb unit cells are welded to form a honeycomb chain, the honeycomb chain is laminated and glued to two adjacent honeycomb chain layers, and the side edges of the honeycomb unit cells are symmetrically connected with a small rib plate with respect to a center cylinder. The sandwich panel improvesthe specific stiffness and specific strength of the honeycomb sandwich panel bearing an out-of-plane load by using the characteristics of cylindrical axial compression stabilization and plastic energyabsorption, so that the panel is stressed more evenly; mechanical properties of a honeycomb core and the capability of bearing the out-of-plane load are enhanced, and the compression, bending and impact resistance of the honeycomb sandwich panel is improved.

Novel configuration honeycomb sandwich panel

The invention discloses a negative poisson ratio honeycomb structure based on a bistable composite material expandable cylindrical shell The negative poisson ratio honeycomb structure consists of a plurality of honeycomb cell structures arranged in a staggered manner, wherein the honeycomb cell structures are in bistable composite material cylindrical shell honeycomb cell structures consisting of bistable cylindrical shell rods and connection round tubes, one end of each of four bistable composite material cylindrical shell rods is connected to one connection round tube of which the curling stability curvature radius is consistent with those of the bistable composite material cylindrical shell rods, and the other ends of four bistable composite material cylindrical shell rods are connected with the connection round tubes of the other honeycomb cell structures, thereby forming the honeycomb structure with the negative poisson ratio characteristic Different from a honeycomb cell structure adopting a flat plate support, the negative poisson ratio honeycomb structure adopts the composite material cylindrical shell rods with the bistable characteristic, so that the expandsion support stiffness of the formed negative poisson ratio honeycomb structure can be improved; during compression, the negative poisson ratio honeycomb structure automatically curls and contracts; a phenomenon of larger range bucking when the flat plate structure is adopted is avoided; the negative poisson ratio effect and the structural stiffness of the negative poisson ratio honeycomb structure can be improved greatly; and the structural reliability can be improved

Negative poisson ratio honeycomb structure based on bistable composite material expandable cylindrical shell

The embodiment of the invention discloses a metal spring for a flexible cover, and relates to the field of structural design of flexible covers. The dual characteristics required by the flexible cover can be met while cost control is guaranteed. The metal spring for the flexible cover is composed of curved sections and straight sections at intervals in the two-dimensional plane, each straight section is arranged between the corresponding two adjacent curved sections, and the curved sections are elliptic arcs. In a fiber reinforced body formed by the metal springs, the metal springs are arranged in a grid mode, horizontal and vertical fibers of grids intersect at the straight sections of the metal springs. The metal spring is made of a high-elasticity steel material. The metal spring is suitable for the flexible cover of a self-adaptive bump air duct.

Metal spring for flexible cover

The invention discloses an engine cover cap protection structure for pedestrian protection. The engine cover cap protection structure comprises an upper panel and a lower panel, wherein a protection structure body is arranged between the upper panel and the lower panel. The protection structure body comprises a plurality of annular structural single bodies, and the adjacent annular structural single bodies are connected to each other by connecting rods to form a whole. The uppermost annular structural single bodies are tangentially connected with the bottom surface of the upper panel, and thelowermost annular structural single bodies are tangentially connected with the upper surface of the lower panel. The engine cover cap protection structure for pedestrian protection mainly utilizes annular structures which are placed between an engine cover cap and a cover plate in a telescoping mode and have good energy absorption effect, and the engine cover cap protection structure can be rotated and deployed to form a complete protective structure body with lifting of the engine cover cap. When a pedestrian collides with a car and causes the head to hit the engine cover cap, the connectingrods and the annular structures are deformed to absorb the collision energy, and thus the effect of protecting the head of the pedestrian is achieved.

Engine cover cap protection structure for pedestrian protection

The invention provides a method for calculating axial compressive stress of a novel quadrilateral chiral honeycomb. The method comprises the following steps: step 1, based on geometric configuration of the quadrilateral chiral cell-element honeycomb, calculating total energy absorbed by a telescopic unit; step 2, calculating total energy absorbed by four additional plane units; and step 3, based on the total energy absorbed by the telescopic unit and the total energy absorbed by the four additional plane units, which are calculated in the steps 1 and 2, calculating the axial compressive stress of the quadrilateral chiral cell-element honeycomb under axial compression according to an energy conservation principle. According to the method, a theoretical method for calculating the axial compression stress is given out in combination with a super folding unit theory based on the energy conservation principle, and the axial compression of the quadrilateral chiral cell-element honeycomb is simulated by applying a finite element simulation technology, so that the correctness of the theoretical calculation method is verified.

Method for calculating axial compressive stress of novel quadrilateral chiral honeycomb

The invention provides a method for calculating double reinforced regular hexagon honeycomb axial compressive stress. The method comprises the following steps of: step1, based on a geometrical configuration of a double reinforced regular hexagon honeycomb, calculating total bending deformation energy absorbed by four additional plane units; step 2, calculating total thin film deformation energy absorbed by four additional plane units; step 3, based on energy conservation, according to the total bending deformation energy and total thin film deformation energy obtained in the above steps, calculating axial compressive stress of the double reinforced regular hexagon honeycomb under the axial compression. The method disclosed by the invention is not limited to predict the static mechanical properties and explain the deformation mechanism, and can calculate the axial compressive stress by using super-folded element theory based on the principle of conservation of energy. The calculation method has the advantages of simple analytical expression, high precision and high reliability and can rapidly judge energy absorption ability of the honeycomb energy-absorbing devices of different cell-element sizes.

Method for calculating double reinforced regular hexagon honeycomb axial compressive stress

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Method for calculating axial compressive stress of novel quadrilateral chiral honeycomb

Method for calculating double reinforced regular hexagon honeycomb axial compressive stress