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塑料焊接原理

顆粒增強型塑料的超聲波衰減（一）

目前各種類型的顆粒增強型聚合物複合材料已得到廣泛應用。爲了表征它們的動態特性，許多學者研究了彈性波在顆粒增強型聚合物複合材料中的傳播，包括超聲測試技術以及基于各種波散射模型的理論研究[16-27]。超聲波在顆粒增強型聚合物複合材料中衰減顯著，聲波的衰減屬于粘滯性衰減和散射衰減同時存在的複雜過程。這些衰減機制的相對份額不僅會隨著組成物(基體和顆粒)的聲學特性而改變，而且與顆粒尺寸、粒子濃度和檢測聲波的頻率範圍有關。研究超聲波在不同顆粒增強型聚合物複合材料中的衰減預測模型，對于理解以衰減爲基礎的材料評價，或設計並優化探頭背襯的衰減性能有重要意義。

除此之外，Beltzer 和Brauner用公式推导了体波和SH(水平剪切)波在复合材料中的散射，即所谓的微分法，将微分学用于由两相组成的复合材料性能的研究。这种方法的优点在于，在颗粒浓度较低时，相对简单的微观力学(机理)表达式可以用增量形式表示。

针对超声波纵波在一些颗粒增强型聚合物复合材料中的衰减，有人以微分(增量)算法为基础对微观机械(力学)模型进行了理论研究，并建立了一系列的微分公式，从已知的粘滞性基体和弹性颗粒的性能(参数)可以计算出复合材料的衰减谱。S. Biwa等人详细研究了颗粒增强型聚合物复合材料的纵波衰减谱与波长-颗粒半径的比值以及粒子体积分数之间的关系。理论分析表明，当颗粒半径与入射波长相比足够小时，超声波的衰减随着粒子体积分数的增加单调减小，而当颗粒半径-波长的比值较大时，衰减与粒子体积分数不呈单调变化。为了从实验角度对理论进行验证，测量了颗粒半径尺寸为0.0225mm的玻璃相颗粒增强型聚合物复合材料在不同粒子体积分数时的纵波衰减。对于颗粒半径尺寸为0.15mm的玻璃相颗粒增强型聚合物复合材料，与先前的独立散射模型相比，本研究提出的分析方法与实测结果符合得较好。结果表明，从定性角度来看，实验测量得到的衰减特性与理论预测相符。

顆粒增強複合材料由各向同性的粘滯性基體(複合拉梅常數爲，；密度)和隨機分布的各向同性彈性顆粒(彈性拉梅常數爲，；密度 ,半徑a)組成，如圖11-12所示。

在微分法中，對因顆粒含量的微小增量而導致的複合材料宏觀性質的改變，以增量形式給出。因此可以把顆粒體積分數爲Φ的複合材料看做是具有等效宏觀性質的有效均勻介質，其對應的彈性參數爲(λ,μ；密度p)。

靈科超聲波堅持自主研發，最大力度投入研發設計，擁有一支近30年的研發制造團隊，發明創造170余項專利新技術。主要品牌有LINGGAO靈高、LINGKE靈科、SHENGFENG聲峰等。廣泛運用在醫療器械、電子器材、打印耗材、塑料、無紡布、包裝、汽配等多個領域，爲海內外各行業、企業提供了大量穩定性強的優質超聲波塑焊設備及應用方案。

塑料焊接在汽車行業中的應用

常見塑料焊接問題的解決辦法（一）

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