CN114347585A - Sandwich structure of local compact honeycomb core - Google Patents
Sandwich structure of local compact honeycomb core Download PDFInfo
- Publication number
- CN114347585A CN114347585A CN202111631930.3A CN202111631930A CN114347585A CN 114347585 A CN114347585 A CN 114347585A CN 202111631930 A CN202111631930 A CN 202111631930A CN 114347585 A CN114347585 A CN 114347585A
- Authority
- CN
- China
- Prior art keywords
- honeycomb core
- local
- core body
- compact
- sandwich
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Abstract
The invention provides a sandwich structure of a local compact honeycomb core, which is characterized in that the core structure of the sandwich plate is subjected to local compact treatment on the basis of a common uniform honeycomb structure. The existence of a local compact structure in the honeycomb core body destroys the uniformity of the core body, changes the load transfer path of the sandwich plate structure under the action of compressive load, reduces the stress concentration existing in the structure, increases the bonding area of the surface core and improves the energy absorption of the structure. Test results show that the carbon fiber sandwich structure of the partially-compact honeycomb core can enable the structure to generate a synergistic destruction effect, and the specific energy absorption of the structure is remarkably improved under the condition that the fluctuation range of the peak load of the sandwich plate structure is small.
Description
Technical Field
The invention relates to a composite material local compact honeycomb sandwich structure which can effectively improve the energy absorption of the structure on the premise of ensuring light weight and no damage to a skin.
Background
The honeycomb material consists of a continuous multi-wall surface arrangement and a hexagonal reticular structure, and the structure can effectively disperse external force from all directions, so that the honeycomb structure has higher resistance to extrusion than structures in other shapes. The sandwich board with the honeycomb as the core has the characteristics of light weight, specific stiffness, high specific strength and the like, and can absorb great energy and protect other structures from being damaged before bearing load and compressing the sandwich board to a more stable state. Therefore, the honeycomb core sandwich board is widely applied to different industrial fields such as aviation, aerospace, automobiles, packaging, ships, military, traffic, buildings and the like as a material of a protective structure. However, in the past, the core body structure is changed to change the mechanical properties of the sandwich panel, so that the core body manufacturing process is too complex, the mechanical properties of the whole structure are not good, and the like, and a large space still exists for the development of more mechanical properties of the honeycomb core sandwich structure at present.
The method is inspired by the phosphene of a corrugated honeycomb structure in the two-dimensional material graphene, and based on the hyper-folding unit theory and the assumption of introducing initial damage, local densification treatment is carried out on the basis of the original uniform honeycomb core body. The existence of a local compact structure in the honeycomb core body destroys the uniformity of the core body, changes the load transfer path of the sandwich plate structure under the action of compressive load, reduces the stress concentration existing in the structure, increases the bonding area of the surface core and improves the energy absorption of the structure. Test results show that the carbon fiber sandwich structure of the partially-compact honeycomb core can enable the structure to generate a synergistic destruction effect, and the specific energy absorption of the structure is remarkably improved under the condition that the fluctuation range of the peak load of the sandwich plate structure is small.
Disclosure of Invention
The invention provides a carbon fiber sandwich structure of a partially compact honeycomb core, aiming at the problem of how to enable a composite sandwich plate to exert more advantages in the aspect of energy absorption.
The technical scheme adopted by the invention is as follows:
a sandwich structure of a local compact honeycomb core comprises an upper skin 1, a lower skin 4, a honeycomb core 2 and a local compact structure 3; the upper skin 1 and the lower skin 4 are made of metal materials or composite materials made of carbon fibers and glass fibers; the honeycomb core body 2 consists of cylinder unit cells without upper and lower surfaces and with polygonal cross sections; the honeycomb core body 2 is made of metal materials, organic polymer materials or carbon fibers.
The local compact structure 3 is formed by extruding a hole material; the local compact structure 3 and the honeycomb core body 2 are integrally molded to form the local compact honeycomb core body.
The local compact honeycomb core body is connected with the upper skin 1 and the lower skin 4 through resin curing to form a sandwich structure of the local compact honeycomb core body.
The sandwich structure of the local compact honeycomb core body is formed in one step by sequentially laying a lower skin 4, the local compact honeycomb core body and an upper skin 1 in a die and carrying out hot pressing and curing on the whole.
In order to ensure that the local compact structures 3 play a synergistic role of the skins and the honeycomb cores 2, the interval between the local compact structures 3 is not less than two honeycomb core 2 unit cells and not more than five honeycomb core 2 unit cells, the local compact structures in the horizontal direction are perpendicular to the local compact structures in the vertical direction, and the whole local compact structures are distributed in a grid shape.
In order to ensure that the local compact honeycomb core body has a good local compact effect, at least two local compact structures 3 are arranged on the surface of the local compact honeycomb core body in the horizontal and vertical directions in the honeycomb core body 2; the proportion of the local compact structure in the area of the core body is not less than 0.19%; the total number of honeycomb unit cells of each core area divided by the local compact structure is not less than six.
The sandwich structure of the local compact honeycomb core body is manufactured into a plate, beam or energy-absorbing tube structure form according to engineering requirements.
According to the invention, the carbon fiber sandwich structure of the local compact honeycomb core body is used, so that the contact area between the core body and the skin can be increased on the premise of not damaging the skin, and the bonding effect of the surface core is further enhanced; due to the existence of the local compact structure, the stress concentration position and the force transmission path in the structure are changed, so that the skin and the core body are crushed in a coordinated manner in the compression process of the structure, and the energy absorption value of the structure is finally greatly improved; meanwhile, the structure has high quality utilization rate, thereby saving materials and having good economic benefit.
The sandwich structure of the local compact honeycomb core body can effectively avoid integral buckling in the compression process; the initial damage introduced by the locally dense core structure changes the peak load of the sandwich structure under compression to a certain extent, and the magnitude of the value is related to the length-width ratio of the test piece, so that the test piece can be designed for different working environments according to different length-width ratios in practical application.
The local compact structure in the local compact honeycomb core body is directly formed by reforming a common uniform honeycomb core body without introducing a new material structure, and the whole local compact honeycomb core body has the same material structure and better overall performance; the height of the local compact honeycomb core sandwich plate structure is consistent with that of a common uniform honeycomb core sandwich plate structure, the structure size is not obviously changed, the manufacturing process of the local compact honeycomb core is simple, and the local compact honeycomb core sandwich plate structure is convenient to improve on the basis of the existing design; meanwhile, the structure of the invention also has good sound absorption effect.
Drawings
Figure 1 is a schematic view of a partially densified honeycomb core.
Fig. 2 is a schematic plan view of a carbon fiber sandwich structure of a partially densified honeycomb core.
Fig. 3 is a three-dimensional schematic view of a carbon fiber sandwich structure of a partially densified honeycomb core.
FIG. 4 is a quasi-static compression test load displacement curve of a common uniform honeycomb core sandwich plate test piece with a total length of 83mm, a total width of 46mm and a total height of 17.4mm and a sandwich plate test piece with a partially compact honeycomb core under a loading rate of 1 mm/min.
Fig. 5 shows the final failure mode of a common uniform honeycomb core sandwich plate test piece with a total length of 83mm, a total width of 46mm and a total height of 17.4mm and a sandwich plate test piece with a locally dense honeycomb core at a loading rate of 1mm/min, wherein (a) shows the failure process mode of the common uniform honeycomb core sandwich plate test piece, and (b) shows the failure process mode of the sandwich plate test piece with the locally dense honeycomb core.
FIG. 6 is a load displacement curve of quasi-static compression test at a loading rate of 1mm/min for a common uniform honeycomb core sandwich plate test piece with a total length of 100mm, a total width of 90mm and a total height of 17.4mm and a sandwich plate test piece of a partially dense honeycomb core.
Fig. 7 shows the failure process mode of a common uniform honeycomb core sandwich plate test piece with a total length of 100mm, a total width of 90mm and a total height of 17.4mm and a sandwich plate test piece of a partially compact honeycomb core at a loading rate of 1mm/min, (a) shows the failure process mode of the common uniform honeycomb core sandwich plate test piece, and (b) shows the failure process mode of the sandwich plate test piece of the partially compact honeycomb core.
In the figure: 3, local compact structure; 2 a honeycomb core; 1, covering an upper skin; 4 lower skin.
Detailed Description
The invention relates to a sandwich structure of a local compact honeycomb core, which comprises an upper skin, a lower skin and the local compact honeycomb core, wherein the local compact honeycomb core is formed by reforming a common uniform honeycomb core to form a local compact structure with a certain special shape.
Specific example 1: the carbon fiber sandwich board of the local compact aluminum honeycomb core body is characterized in that an upper skin and a lower skin of the carbon fiber sandwich board are both made of 6 layers of unidirectional carbon fiber cloth and LY5288/HY5289 epoxy resin, wherein the 6 layers of carbon fiber cloth are laid in the same direction, and the height (thickness) of the skins is 0.9 mm; the aperture of the aluminum honeycomb is 6mm, the wall thickness of the hole is 0.06mm, and the height is 15 mm.
The method comprises the following steps of respectively carrying out local densification treatment on a common uniform aluminum honeycomb core body in the horizontal direction and the vertical direction, forming a lattice shape by using a treated local densification structure to divide a test piece into 9 rectangular areas, wherein 5 unit cells are arranged between two transverse local densification structures, 2 unit cells are arranged between two longitudinal local densification structures, and each area at least comprises 6 honeycomb unit cells. The area ratio of the local dense structure to the core body is 0.31%. As shown in fig. 3.
The material is paved in a mould in sequence by pressing a covering, a local compact aluminum honeycomb core body and an upper covering, and is integrally hot-pressed and solidified in a hot press; the pressure of the hot press is 0.6MPa, during hot pressing, the hot press is heated to 50 ℃ at the heating rate of 3 ℃/min, the temperature is kept for half an hour, then the hot press is heated to 80 ℃ at the heating rate of 3 ℃/min, the temperature is kept for half an hour, then the hot press is naturally cooled to the room temperature, and the mold is opened to obtain the carbon fiber sandwich board of the partially compact aluminum honeycomb core.
The obtained sandwich panel was cut into a sandwich panel having a total length of 83mm, a total width of 46mm and a total height of 16.8 mm. And designing a quasi-static compression test, wherein the loading mode is displacement loading.
Fig. 4 shows the load displacement curve of the common uniform aluminum honeycomb sandwich plate and the local compact aluminum honeycomb sandwich plate test piece when the loading rate is 1mm/min, and 5 test pieces of the common uniform aluminum honeycomb sandwich plate and the local compact aluminum honeycomb sandwich plate participate in the test. The results show that the bending stiffness of the partially densified aluminum honeycomb sandwich panel test piece is basically consistent with that of the common uniform aluminum honeycomb sandwich panel test piece in the initial loading stage, and the test pieces are all shown to be end shear failure. In the damage stage, along with the deepening of the loading process, the general uniform aluminum honeycomb sandwich plate test piece is integrally bent and accompanied by the surface-core separation phenomenon, and large-area debonding or direct shedding occurs at the position of the loading stroke of about 30 mm; the local compact aluminum honeycomb sandwich plate test piece is always in a vertical compression state along with the continuous increase of displacement load, the skin and the core are gradually crushed in a synergetic mode until the compression is about 60mm, and the core loses the bearing capacity in an extreme compression state. Five test piece load-displacement curves of the common uniform aluminum honeycomb sandwich plate show the same trend, sudden reduction occurs after peak load, and the common uniform aluminum honeycomb sandwich plate is kept stable at a smaller load value and has smaller discreteness; the load-displacement curve of the local compact aluminum honeycomb sandwich plate test piece at the initial stage of damage is not much different from that of the common uniform aluminum honeycomb sandwich plate test piece, but the peak load is slightly higher, subsequent damage-reinforcement-re-damage cycles frequently occur, and the load peak value is slowly reduced.
On one hand, the local compact structure destroys the uniformity of the honeycomb core body and changes the stress concentration position and the load transfer path in the compression process of the sandwich plate; on the other hand, on the premise of not damaging the skin, the contact area between the core body and the skin is increased, so that the bonding effect of the surface core is enhanced, and the structural integrity of the structure is prevented from being damaged due to the premature surface core debonding. The core body is provided with a local compact structure, so that the skin and the core body are crushed gradually in a synergetic mode in the compression process of the sandwich board, and the energy absorption value of the structure is greatly improved under the condition that the peak load variation amplitude is small. The resin matrix of the surface core interface of a common uniform aluminum honeycomb sandwich panel test piece is relatively uniformly distributed, but the interface bonding strength is poor, so that the phenomenon of interface delamination failure can occur earlier, and the sandwich panel loses structural integrity earlier. At this time, the upper and lower skins can only provide bending rigidity by taking the respective middle planes as neutral planes, and cannot take the middle plane of the sandwich structure as a neutral plane, so that the bearing capacity of the structure is rapidly reduced.
Fig. 5 shows the failure process mode of the common uniform aluminum honeycomb sandwich panel and the partially densified aluminum honeycomb sandwich panel test piece, and by observing the failure interface of the test piece, the end face of the common uniform aluminum honeycomb sandwich panel at the failure initial stage can form obvious shear failure cracks, the surface core interface of the sandwich panel at the failure middle stage can form obvious cracks, and the skin and the core body after the failure can be debonded or fall off in a large area; the initial failure of the local compact aluminum honeycomb sandwich plate test piece is slight shear failure of the end face, and the failure from the middle stage to the later stage is represented by the cooperative gradual crushing of the skin and the core.
Table 1 shows the average limit load and average energy absorption comparison of a common uniform aluminum honeycomb sandwich plate and a partially densified aluminum honeycomb sandwich plate test piece when the loading rate is 1mm/min, the average limit load of the partially densified aluminum honeycomb sandwich plate test piece is 14.47KN, and the average limit load is improved by 13.97% compared with 12.69KN of the common uniform aluminum honeycomb sandwich plate; the average energy absorption of the partially compact aluminum honeycomb sandwich plate test piece is 259.07J, and compared with 73.02J of a common uniform aluminum honeycomb sandwich plate, the average energy absorption is improved by 254.79%.
TABLE 11 comparison of ultimate load and absorbed energy for two sandwich panels at mm/min load rate
| Sandwich type | Common uniform aluminium honeycomb core | Local compact aluminium honeycomb core |
| Average ultimate load (KN) | 12.69 | 14.47 |
| Percent increase in mean ultimate load (%) | — | 13.97％ |
| Average energy absorption (J) | 73.02 | 259.07 |
| Percent increase in average energy absorption (%) | — | 254.79％ |
Specific example 2: the honeycomb core body of the local compact aluminum honeycomb sandwich board has 5 single cells in total between two transverse local compact structures and 5 single cells in total between two longitudinal local compact structures. The test pieces had a total length of 100mm, a total width of 90mm and a total height of 16.8 mm. The partially dense structure accounted for 0.19% of the core area. The preparation process of the sandwich plate is the same as that of the sandwich plate in the embodiment 1, and the displacement loading rate of the quasi-static compression experiment is 1 mm/min.
Fig. 6 shows the load displacement curves of the common uniform aluminum honeycomb sandwich panel test piece and the local compact aluminum honeycomb sandwich panel test piece when the displacement loading rate is 1mm/min, wherein 3 test pieces of the common uniform aluminum honeycomb sandwich panel and the local compact aluminum honeycomb sandwich panel participate in the test. It can be seen from the figure that the load displacement curve of the partially densified aluminum honeycomb sandwich plate test piece is basically above the load displacement curve of the common uniform aluminum honeycomb sandwich plate test piece, which shows that the load bearing capacity and the energy absorption performance of the test piece using the partially densified aluminum honeycomb core body are obviously superior to those of the common uniform core body test piece in the quasi-static compression process. Compared with the embodiment 1, the test pieces are different in size and length-width ratio, and the limit load and the energy absorption of the two groups of test ordinary uniform aluminum honeycomb sandwich plate/local compact aluminum honeycomb sandwich plate test pieces are different to a certain extent, but the local compact aluminum honeycomb sandwich plate test pieces show excellent energy absorption effect.
Fig. 7 shows the final failure mode of the test piece using the common uniform aluminum honeycomb sandwich panel and the test piece using the partially densified aluminum honeycomb sandwich panel, and it can be seen that the main failure mode of the common uniform aluminum honeycomb sandwich panel test piece is interface debonding failure, and the test piece is bent to different degrees; the test piece of the partially compact aluminum honeycomb sandwich plate is mainly subjected to slight shear failure at the end part, which shows that the toughness of the surface-core interface is effectively improved on the premise that the integrity of the skin is not damaged by the partially compact aluminum honeycomb sandwich plate.
Table 2 shows the average limit load and average energy absorption comparison of a common uniform aluminum honeycomb sandwich plate/local compact aluminum honeycomb sandwich plate test piece when the displacement loading rate is 1mm/min, the average limit load of the local compact aluminum honeycomb sandwich plate test piece is 29.69KN, the average limit load of the common uniform aluminum honeycomb sandwich plate test piece is 30.37KN, and the average limit load is reduced by 2.24%; the average energy absorption of the partially compact aluminum honeycomb sandwich plate test piece is 182.83J, the average energy absorption of the common uniform aluminum honeycomb sandwich plate test piece is 63.09J, and the average energy absorption is improved by 189.79%.
TABLE 21 comparison of ultimate load and absorbed energy for two sandwich panels at mm/min load rate
The results show that the local compact honeycomb sandwich structure provided by the invention has excellent energy absorption performance.
Claims (5)
1. The sandwich structure of the local compact honeycomb core is characterized in that the sandwich structure of the special-shaped honeycomb core comprises an upper skin (1), a lower skin (4), a honeycomb core (2) and a local compact structure (3);
the upper skin (1) and the lower skin (4) are made of metal materials or composite materials;
the honeycomb core body (2) consists of cylinder unit cells without upper and lower surfaces and with polygonal cross sections; the honeycomb core body (2) is made of metal materials, organic polymer materials or carbon fibers;
the local compact structure (3) is formed by extruding a hole material;
the local compact structure (3) and the honeycomb core body (2) are integrally molded to form a local compact honeycomb core body;
the local compact honeycomb core body is connected with the upper skin (1) and the lower skin (4) through resin curing to form a sandwich structure of the local compact honeycomb core body;
in order to ensure that the local compact structure plays a role in changing a force transmission path, at least two local compact structures (3) are arranged in the honeycomb core body (2) in the transverse and longitudinal directions respectively; the proportion of the local compact structure in the area of the core body is not less than 0.19%; the total number of unit cells of each honeycomb core area divided by the partially dense structure must not be less than six.
2. The sandwich structure of the local dense honeycomb core body according to claim 1, wherein in order to ensure that the local dense structure (3) plays a synergistic role of the skin and the honeycomb core body (2), the interval between the local dense structure (3) is not less than two single cells of the honeycomb core body (2) and not more than five single cells of the honeycomb core body (2), the local dense structure in the horizontal direction is perpendicular to the local dense structure in the vertical direction, and the whole local dense structure is distributed in a grid shape.
3. The sandwich structure of the partially densified honeycomb core according to claim 1 or 2, wherein the sandwich structure of the partially densified honeycomb core is formed in one step by sequentially laying a lower skin (4), the partially densified honeycomb core and an upper skin (1) in a mold and curing the whole by hot pressing.
4. The sandwich structure of a partially densified honeycomb core according to claim 3, wherein the composite material is made of carbon fibers, glass fibers, or ceramic fibers.
5. The sandwich structure of a partially densified honeycomb core according to claim 1, 2 or 4, wherein the sandwich structure is manufactured in the form of a plate, a beam or an energy absorbing tube structure according to engineering requirements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111631930.3A CN114347585B (en) | 2021-12-29 | 2021-12-29 | Sandwich structure of local compact honeycomb core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111631930.3A CN114347585B (en) | 2021-12-29 | 2021-12-29 | Sandwich structure of local compact honeycomb core |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114347585A true CN114347585A (en) | 2022-04-15 |
| CN114347585B CN114347585B (en) | 2023-03-03 |
Family
ID=81104184
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111631930.3A Active CN114347585B (en) | 2021-12-29 | 2021-12-29 | Sandwich structure of local compact honeycomb core |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114347585B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115320183A (en) * | 2022-08-22 | 2022-11-11 | 大连交通大学 | Honeycomb core with S-shaped reinforcing structure |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB794217A (en) * | 1955-12-09 | 1958-04-30 | Blackburn & General Aircraft L | Improvements in or relating to honeycomb and like fabricated cellular material |
| US20150118436A1 (en) * | 2013-10-28 | 2015-04-30 | Airbus Helicopters Deutschland GmbH | Skin-stiffened composite panel |
| CN105128412A (en) * | 2015-08-14 | 2015-12-09 | 大连理工大学 | Sandwich structure with mesh reinforced honeycomb core body |
-
2021
- 2021-12-29 CN CN202111631930.3A patent/CN114347585B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB794217A (en) * | 1955-12-09 | 1958-04-30 | Blackburn & General Aircraft L | Improvements in or relating to honeycomb and like fabricated cellular material |
| US20150118436A1 (en) * | 2013-10-28 | 2015-04-30 | Airbus Helicopters Deutschland GmbH | Skin-stiffened composite panel |
| CN105128412A (en) * | 2015-08-14 | 2015-12-09 | 大连理工大学 | Sandwich structure with mesh reinforced honeycomb core body |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115320183A (en) * | 2022-08-22 | 2022-11-11 | 大连交通大学 | Honeycomb core with S-shaped reinforcing structure |
| CN115320183B (en) * | 2022-08-22 | 2024-01-16 | 大连交通大学 | Honeycomb core with S-configuration reinforcing structure |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114347585B (en) | 2023-03-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102343680B (en) | Mould and method for integrally forming fiber reinforced hexagonal honeycomb-structured core | |
| CN105128412B (en) | Sandwich structure with grid enhancing cellular-core | |
| CN110406178B (en) | Metal/composite material multilayer dual-gradient energy-absorbing and vibration-damping sandwich structure and preparation method thereof | |
| CN108789962B (en) | Mould for preparing composite material reinforced structure | |
| CN114347585B (en) | Sandwich structure of local compact honeycomb core | |
| CN110143034B (en) | Forming method of fiber-aluminum alloy composite material part | |
| CN111171540A (en) | Low-density low-pressure sheet molding compound and preparation method thereof | |
| CN109501397A (en) | A kind of cellular composite material | |
| CN105965930A (en) | Preparing method for inner hexagon negative poisson ratio honeycomb | |
| TW201925281A (en) | Method of manufacturing multi-layer thermoplastic composite sheet with continuous-discontinuous fibers | |
| CN104589731B (en) | Rectangular pyramid resin base truss core foamed composite flat board and manufacture method | |
| CN111873558A (en) | Enhanced aramid honeycomb sandwich plate | |
| CN113915274B (en) | Star-diamond negative Poisson ratio structure | |
| CN108757794B (en) | Composite material tensile energy-absorbing member and preparation method thereof | |
| CN109572075B (en) | Sandwich structure of fiber tape toughening honeycomb core | |
| CN115991014A (en) | Carbon fiber microstructure material and preparation method thereof | |
| CN112318895B (en) | Spatial light high-rigidity porous grid carbon fiber honeycomb, and preparation method and application thereof | |
| CN109130238B (en) | Method for manufacturing rear floor beam | |
| CN113752668B (en) | Preparation method of fiber metal laminate with leaf vein bionic negative poisson ratio structure | |
| CN204249171U (en) | Full-automatic glass steel dismoulding system | |
| Chen et al. | Preparation and performance of continuous glass fiber reinforced polypropylene composite honeycomb sandwich panels | |
| CN220053100U (en) | Foam sandwich panel with negative poisson ratio effect | |
| CN115320183B (en) | Honeycomb core with S-configuration reinforcing structure | |
| CN114801258B (en) | Preparation method of bidirectional grille structure reinforced foam sandwich composite material | |
| CN220742363U (en) | High-strength composite aluminum plate |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |