During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is spr...During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is sprayed manually.Furthermore,it can also affect the permeability of the preform,resin injection and the quality of the vacuum assisted resin infusion(VARI)molding,resulting in a decrease in the mechanical properties of composite materials.This study utilizes dry fiber automated placement equipment and an automated spraying system to manufacture preform structures,followed by VARI process to prepare composite samples with varying setting agent contents.Subsequently,mechanical characterization including interlaminar shear,bending and tensile testing is conducted to investigate the influence of setting agent content on both the manufacturing process and the mechanical properties of composite products.The results show that the interlaminar shear strength,bending strength and tensile strength of the sample gradually decrease with the increase of the content of the setting agent.The optimal setting agent content for automated laying of dry fiber is determined to be 4%-6%,balancing the preformed body’s layup quality and its impact on mechanical properties.Compared with agent-free samples,this range results in reductions of 3% in interlaminar shear strength,9% in bending strength,11% in bending modulus,and 13%-16% in tensile strength.展开更多
[Objective] The paper was to study the effects of different drying methods on moisture content and nutrient composition of alfalfa.[Method] Alfalfa collected from the same piece of land in early flowering period were ...[Objective] The paper was to study the effects of different drying methods on moisture content and nutrient composition of alfalfa.[Method] Alfalfa collected from the same piece of land in early flowering period were dried through three different drying methods, solar drying,outdoor drying in the sun and outdoor drying in the shade, and the effects of different drying methods on contents of moisture, crude protein, crude ash and neutral detergent fiber（NDF） were measured. [Result] The moisture evaporation rate of different drying methods over the same period successively were solar drying 〉 outdoor drying in the sun 〉 outdoor drying in the shade. The crude protein content of alfalfa was the highest through solar drying（P〈0.05）, followed by outdoor drying in the shade, and the crude protein content through outdoor drying in the sun was the lowest. Under the condition of different moisture contents, the crude protein content of dried samples through outdoor drying in the sun decreased by 6.86%-22.43% compared to solar drying, and that through outdoor drying in the shade reduced by 4.92%-17.20%. Under the same moisture content, the crude ash content successively were outdoor drying in the shade 〉 outdoor drying in the sun 〉 solar drying; the crude ash content of alfalfa through solar drying was 3.72%-19.22% lower than outdoor drying in the sun, and 8.12%-29.93% lower than outdoor drying in the shade. The NDF content of alfalfa through outdoor drying in the sun was the highest, significantly higher than the other two drying methods（ P〈0.05）. The NDF content through solar drying was the lowest, 9.08%-27.25% lower than outdoor drying in the sun, and 4.84%-24.84% lower than outdoor drying in the shade. [Conclusion] The paper will provide some references for selection of appropriate alfalfa drying method.展开更多
基金supported by Jiangsu Provincial Key Research and Development Program(No.BE2023014-4).
文摘During the automated placement process of dry fibers,the positioning and fixation of dry fiber gauze belts are achieved by spraying setting agents.The amount of the setting agent is difficult to control when it is sprayed manually.Furthermore,it can also affect the permeability of the preform,resin injection and the quality of the vacuum assisted resin infusion(VARI)molding,resulting in a decrease in the mechanical properties of composite materials.This study utilizes dry fiber automated placement equipment and an automated spraying system to manufacture preform structures,followed by VARI process to prepare composite samples with varying setting agent contents.Subsequently,mechanical characterization including interlaminar shear,bending and tensile testing is conducted to investigate the influence of setting agent content on both the manufacturing process and the mechanical properties of composite products.The results show that the interlaminar shear strength,bending strength and tensile strength of the sample gradually decrease with the increase of the content of the setting agent.The optimal setting agent content for automated laying of dry fiber is determined to be 4%-6%,balancing the preformed body’s layup quality and its impact on mechanical properties.Compared with agent-free samples,this range results in reductions of 3% in interlaminar shear strength,9% in bending strength,11% in bending modulus,and 13%-16% in tensile strength.
基金Supported by National Natural Science Foundation of China(51266009)
文摘[Objective] The paper was to study the effects of different drying methods on moisture content and nutrient composition of alfalfa.[Method] Alfalfa collected from the same piece of land in early flowering period were dried through three different drying methods, solar drying,outdoor drying in the sun and outdoor drying in the shade, and the effects of different drying methods on contents of moisture, crude protein, crude ash and neutral detergent fiber（NDF） were measured. [Result] The moisture evaporation rate of different drying methods over the same period successively were solar drying 〉 outdoor drying in the sun 〉 outdoor drying in the shade. The crude protein content of alfalfa was the highest through solar drying（P〈0.05）, followed by outdoor drying in the shade, and the crude protein content through outdoor drying in the sun was the lowest. Under the condition of different moisture contents, the crude protein content of dried samples through outdoor drying in the sun decreased by 6.86%-22.43% compared to solar drying, and that through outdoor drying in the shade reduced by 4.92%-17.20%. Under the same moisture content, the crude ash content successively were outdoor drying in the shade 〉 outdoor drying in the sun 〉 solar drying; the crude ash content of alfalfa through solar drying was 3.72%-19.22% lower than outdoor drying in the sun, and 8.12%-29.93% lower than outdoor drying in the shade. The NDF content of alfalfa through outdoor drying in the sun was the highest, significantly higher than the other two drying methods（ P〈0.05）. The NDF content through solar drying was the lowest, 9.08%-27.25% lower than outdoor drying in the sun, and 4.84%-24.84% lower than outdoor drying in the shade. [Conclusion] The paper will provide some references for selection of appropriate alfalfa drying method.
