Hinderdael Michaël, Jardon Zoé, Lison Margot, De Baere Dieter, Devesse Wim, Strantza Maria, Guillaume Patrick
Department of Mechanical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium.
Vrije Universiteit Brussel, Department of Mechanics of Materials and Constructions, Pleinlaan 2, 1050 Elsene, Belgium.
Sensors (Basel). 2017 Feb 9;17(2):328. doi: 10.3390/s17020328.
Currently, research on structural health monitoring systems is focused on direct integration of the system into a component or structure. The latter results in a so-called smart structure. One example of a smart structure is a component with integrated strain sensing for continuous load monitoring. Additive manufacturing, or 3D printing, now also enables such integration of functions inside components. As a proof-of-concept, the Fused Deposition Modeling (FDM) technique was used to integrate a strain sensing element inside polymer (ABS) tensile test samples. The strain sensing element consisted of a closed capillary filled with a fluid and connected to an externally mounted pressure sensor. The volumetric deformation of the integrated capillary resulted in pressure changes in the fluid. The obtained pressure measurements during tensile testing are reported in this paper and compared to state-of-the-art extensometer measurements. The sensitivity of the 3D printed pressure-based strain sensor is primarily a function of the compressibility of the capillary fluid. Air- and watertightness are of critical importance for the proper functioning of the 3D printed pressure-based strain sensor. Therefore, the best after-treatment procedure was selected on basis of a comparative analysis. The obtained pressure measurements are linear with respect to the extensometer readings, and the uncertainty on the strain measurement of a capillary filled with water (incompressible fluid) is ±3.1 µstrain, which is approximately three times less sensitive than conventional strain gauges (±1 µstrain), but 32 times more sensitive than the same sensor based on air (compressible fluid) (±101 µstrain).
目前，结构健康监测系统的研究重点是将该系统直接集成到部件或结构中。后者会产生所谓的智能结构。智能结构的一个例子是带有集成应变传感功能以进行连续载荷监测的部件。增材制造，即3D打印，现在也能够实现部件内部功能的这种集成。作为概念验证，熔融沉积建模（FDM）技术被用于在聚合物（ABS）拉伸试验样品内部集成一个应变传感元件。该应变传感元件由一个充满流体的封闭毛细管组成，并连接到一个外部安装的压力传感器。集成毛细管的体积变形导致流体中的压力变化。本文报告了拉伸试验期间获得的压力测量结果，并与最先进的引伸计测量结果进行了比较。3D打印的基于压力的应变传感器的灵敏度主要取决于毛细管流体的可压缩性。气密性和水密性对于3D打印的基于压力的应变传感器的正常运行至关重要。因此，在比较分析的基础上选择了最佳的后处理程序。获得的压力测量结果与引伸计读数呈线性关系，对于充满水（不可压缩流体）的毛细管，应变测量的不确定度为±3.1微应变，其灵敏度约为传统应变片（±1微应变）的三分之一，但比基于空气（可压缩流体）的同一传感器（±101微应变）灵敏32倍。
