To repair the damage to the epoxy/carbon fiber laminate, a single-lap test was performed between sulfuric acid anodized aluminum plate and carbon fiber laminate to study the effect of the anodized layer on the interlaminar shear strength. Then, carbon fiber laminates were prepared by wet-laying method to simulate the damage caused by penetrating cracks, and double-sided adhesive sheets were made from 0.5[Formula: see text]mm thick 2024-T3 aluminum alloy and carbon fiber laminates to match the thickness and material of the simulated damage plate. The adhesive matrix used was E51 bisphenol-A epoxy resin with 1.5[Formula: see text]wt.% nanorubber added for modification and toughening. After double-sided patching, tensile tests were performed to investigate the effect of different materials on the tensile strength of double-sided adhesive patches. We observed SEM images of the fracture surface of the patch after tensile failure and analyzed the strengthening mechanisms of different material patches. The results show that the shear strength between the single-layer sulfuric acid anodized aluminum plate and the carbon fiber laminate is 9.792 MPa, which is 61.5% higher than the shear strength of the nonanodized aluminum plate. The tensile strength of the 2024-T3 aluminum patch specimen is 271.83 MPa, which is 48.43% and 23.97% higher than the perforated specimen without patch and the specimen with carbon fiber laminate patch, respectively, and reaches 72.56% of the undamaged carbon fiber laminate. The specimens with aluminum plate patches showed a maximum bending strength of 616.47 MPa, which increased by 70.83% compared to the 360.875 MPa of the perforated specimens. The maximum bending strength of the aluminum plate patch specimen reached 74.76% of that of the undamaged specimen. However, the maximum bending strength of the composite patch specimen is as high as 1101.9 MPa, far exceeding that of other samples. Due to the poor toughness of the sample, it cannot withstand large strains. The addition of 1.5[Formula: see text]wt.% nanorubber results in shear yield bands and induces silver grains to absorb a large amount of energy during stress deformation.
Interlaminar fracture failure is the main factor restricting the development and application of fiber metal laminates. In this paper, the interlayer bonding properties of 2024-T3 aluminum alloy plates with different surface treatments were compared and studied through lap-shear experiments. Compared with the aluminum plate treated with acid and alkali corrosion, the interlaminar shear strength of the aluminum plate after sulfuric acid anodization increased by 34.3%. After different surface treatments, experimental stressstrain curves of 2024-T3 aluminum alloys reveal the enhancement mechanism and changing trend of interlaminar shear strength.
To find out the genuine characteristics of Eucommia ulmoides produced in Guizhou.The habitat, functional characters and the content of medicinal components of Eucommia ulmoides in Guizhou were studied by using the method of sample survey combined with typical survey, related laboratory experiments and quantitative analysis. The results showed that the yield of Eucommia ulmoides plantation in Guizhou was divided into low altitude, low middle and high temperature rain slope latitude mixing, short sunshine type(A type), medium altitude, low longitude and latitude, high temperature rain, positive oblique steep slope, medium sunshine type (B type), Middle altitude, low longitude and latitude, moderate high temperature rain, Shady side and Sunny side have gentle deflection steep slope, medium sunshine type (C type), High altitude, low longitude and latitude, low temperature moderate rain, positive gentle slope, long sunshine type (D type); Different types of Eucommia ulmoides plantation, Different habitat quality, B type is intensity karst rocky desertification habitat, A type is potential karst rocky desertification habitat,The C and D types are light and moderate rocky desertification areas respectively, The species diversity of shrub layer in Eucommia ulmoides plantation was higher in D type and B type, A type and C type followed; There was no significant difference in root carbon content and leaf nitrogen content in 4 types of Eucommia ulmoides plantation, Among the four types of A、B、C、D, there were significant or extremely significant differences in other indexes of plant functional traits; Both genipinic acid and aucubin had the highest content of root bark, followed by trunk bark and lowest leaves, Chlorogenic acid is the opposite, The content of geniposide was higher in trunk bark and lower in root bark and leaves; Genipinic acid is higher in D type, Aucubin is higher in A and D type, Chlorogenic acid has higher leaves content in B type, Geniposide was the highest in trunk bark of D type; The element enrichment coefficient K and Mn leaves are the largest, the largest in trunk bark is Ca and Zn, Fe root bark is the largest; Effects of soil potassium, phosphorus, pH value and bulk weight on the functional traits of Eucommia ulmoides were significant. The contents of medicinal components in root bark, trunk bark and leaves was influenced by species diversity of shrub layer, The contents of geniposide in root bark, aucubin in root bark and trunk bark, genipinic acid in bark and chlorogenic acid in leaves were particularly affected by soil physical and chemical indexes and metal element contents, The functional traits of Eucommia ulmoides can affect the content of medicinal components in root bark, trunk bark and leaves, Especially on the root bark, trunk bark and leaves in the content of aucubin content; The content of medicinal components of Eucommia ulmoides was high and stable. The above research results have important theoretical reference significance for the cultivation of Eucommia ulmoides and the cultivation of target medicinal components and the comprehensive exploitation and utilization of resources.
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