Proof of Concept of Integrated Load Measurement in 3D Printed Structures

Area of Science:

• Materials Science
• Mechanical Engineering
• Additive Manufacturing

Background:

• Current structural health monitoring focuses on integrating systems into components, creating 'smart structures'.
• Additive manufacturing (3D printing) offers novel methods for integrating sensing functionalities directly within structural components.

Purpose of the Study:

• To demonstrate the feasibility of integrating a pressure-based strain sensing element into polymer samples using Fused Deposition Modeling (FDM).
• To evaluate the performance of the 3D printed strain sensor by comparing its measurements to conventional extensometer data.

Main Methods:

• Utilized Fused Deposition Modeling (FDM) to 3D print ABS tensile test samples with an integrated, fluid-filled capillary strain sensing element.
• Connected the capillary to an external pressure sensor to measure fluid pressure changes corresponding to volumetric deformation during tensile testing.
• Conducted comparative analysis of after-treatment procedures to ensure air- and watertightness of the sensor.

Main Results:

• Obtained pressure measurements from the integrated sensor showed a linear correlation with extensometer readings.
• The uncertainty for strain measurement using a water-filled capillary was ±3.1 µstrain.
• A water-filled sensor demonstrated significantly higher sensitivity (32 times) compared to an air-filled sensor (±101 µstrain).

Conclusions:

• 3D printing enables the integration of functional strain sensing elements within structural components, paving the way for advanced smart structures.
• The sensitivity of the pressure-based strain sensor is highly dependent on the compressibility of the internal fluid.
• The developed 3D printed strain sensor shows promise for structural health monitoring applications, with water-filled sensors offering superior performance.