(清華大學(xué) 機(jī)械工程系，教育部先進(jìn)成形制造重點(diǎn)實(shí)驗(yàn)室，北京 100084)
摘 要: 利用熔體發(fā)泡技術(shù)制備不同孔徑和氣孔率的泡沫鋁，對(duì)不同氣孔率的原始狀態(tài)泡沫鋁以及孔徑為1.1 mm的穿孔泡沫鋁的吸聲性能進(jìn)行研究。結(jié)果表明：未設(shè)置背腔時(shí)，原始狀態(tài)泡沫鋁的吸聲性能不高，設(shè)置背腔后，由于泡沫鋁中所含通透結(jié)構(gòu)的作用，泡沫鋁的吸聲性能明顯提高；穿孔泡沫鋁的穿孔率在0.5%~1.0%范圍，設(shè)置60~80 mm背腔時(shí)可使降噪系數(shù)超過(guò)0.42，比原始狀態(tài)泡沫鋁不設(shè)置背腔時(shí)的降噪系數(shù)高2倍左右；穿孔泡沫鋁設(shè)置背腔后的吸聲特性符合Helmholtz共振吸聲的規(guī)律，但受到穿孔結(jié)構(gòu)、泡沫鋁原本存在的缺陷組成的通透結(jié)構(gòu)和氣泡孔在穿孔過(guò)程中被打開(kāi)的小開(kāi)口等因素的影響。
關(guān)鍵字: 泡沫鋁；穿孔；吸聲性能；Helmholtz共振
（Key Laboratory for Advanced Materials Processing Technology, Ministry of Education,
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China）
Abstract:Aluminum foams with various cell sizes and porosities were prepared by the melt foaming process. The sound absorption properties of aluminum foams with different porosities in as-received state and with drilling holes of 1.1 mm diameter were investigated. The results show that the aluminum foams in as-received state with no back cavity do not possess high sound absorbability, while setting up a back cavity behind the foam can improve the sound absorbability according to some permeable structures existing inside the aluminum foam; the noise reduction coefficients of the aluminum foams with 0.5%−1.0% holes area ratio and 60−80 mm thick back cavity are above 0.42, which are about twice more than that of the aluminum foam in as-received state with no back cavity. The sound absorption coefficients of the aluminum foams with drilling holes comply with the characteristics of Helmholtz-type resonators when a back cavity exists. But they are affected by the structure of the drilling holes, the permeable structures derived from inherent defect inside the aluminum foam and the small openings on the cells formed by drilling process.
Key words: aluminum foam; drilling holes; sound absorption; Helmholtz-type resonator
