Production of a Strain-Measuring Device with an Improved 3D Printer

Summary

This work presents a strain measurement sensor consisting of an amplification mechanism and a polydimethylsiloxane microscope manufactured using an improved 3D printer.

Abstract

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in the analog electrical signal in a traditional strain gauge operation, a new strain measurement method is presented here. It uses a photographic technique to display the strain change by amplifying the change of the pointer displacement of the mechanism. A visual polydimethylsiloxane (PDMS) lens with a focal length of 7.16 mm was added to a smartphone camera to generate a lens group acting as a microscope to capture images. It had an equivalent focal length of 5.74 mm. Acrylonitrile butadiene styrene (ABS) and nylon amplifiers were used to test the influence of different materials on the sensor performance. The production of the amplifiers and PDMS lens is based on improved 3D printing technology. The data obtained were compared with the results from finite element analysis (FEA) to verify their validity. The sensitivity of the ABS amplifier was 36.03 ± 1.34 µε/µm, and the sensitivity of the nylon amplifier was 36.55 ± 0.53 µε/µm.

Introduction

Obtaining light but strong materials is particularly important in modern industry. The properties of materials are affected when subjected to stress, pressure, torsion, and bending vibration during use^1,2. Thus, strain measurement of materials is important to analyze their durability and troubleshoot usage. Such measurements enable engineers to analyze the durability of materials and troubleshoot production problems. The most common strain measurement method in industry uses strain sensors³. Traditional foil sensors are widely used because of their low cost and good reliability

Protocol

1. Assembly of the amplification mechanism

1. Construct an experimental platform including an improved 3D printer, a strain gauge indicator, a driving device, a support frame, an aluminum bar, a PDMS lens, a smartphone, weights, a printed amplifier (Supplemental Figure 1), and a strain gauge, as shown in Figure 1.
2. Set the height of each layer in the printer at 0.05 mm for nylon and 0.2 mm for ABS. Set the diameter of the printing head to 0.2 mm in both cases. Set the temperature of the nozzle to 220 °C for nylon and 100 °C for ABS. Finally, set the printing speed to 2,000 mm/min for nylon and ....

Results

When the platform temperature increased, the droplet diameter and the curvature radius decreased, whereas the contact angle increased (Figure 3). Therefore, the focal length of the PDMS increased. However, for platform temperatures above 220 °C, a very short curing time was observed in the droplets, and they could not extend into a plane-convex shape. This can be attributed to the low attachment area when adhering onto a smartphone camera. Therefore, only soft lenses formed at 220 °C were us.......

Discussion

The output displacement evolved linearly with the force concentrated at the free end of the cantilever beam and was consistent with the FEA simulations. The sensitivity of the amplifiers was 36.55 ± 0.53 με/μm for nylon and 36.03 ± 1.34 με/μm for ABS. The stable sensitivity confirmed the feasibility and the effectiveness of the rapid prototyping of high-precision sensors using 3D printing. The amplifiers had a high sensitivity and were free of electromagnetic interference. In addit.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
ABS	Hengli dejian plastic electrical products factory		Used for printing 1.75 mm diameter wire for amplifying mechanism
Aluminum 6063 T83 bar			The length, width and thickness of cantilever beam are 380 mm, 51 mm, and 3.8 mm.
ANSYS	ANSYS	ANSYS 14.5
CURA	Ultimaker	Cura 3.0	Slicing softare,using with the improved 3D printer
Curing agent	Dow Corning		PDMS and curing agent are mixed with the weight ratio of 10:1
Driving device	Xinmingtian	E00
Improved 3D printer and accessories			Made by myself. The rotary spherical lifting platform is adopted. The spherical lifting platform is equipped with a nozzle and a pipette, which can be switched and printed freely. With a rotary printing platform, the platform temperature can be freely controlled.
iPhone 6	Apple	MG4A2CH/A	8-megapixel sensor and the equivalent focus distance is 29mm
Magenetic stirrer	SCILOGEX	MS-H280-Pro
Nylon	Hengli dejian plastic electrical products factory		Used for printing 1.75 mm diameter wire for amplifying mechanism
PDMS	Dow Corning	SYLGARDDC184	After the viscous mixture is heated and hardened, it can be combined with the lens amplification device of the mobile phone for image acquisition.
Shape analyzer	Gltech	SURFIEW 4000
Solidworks	Dassault Systems	Solidworks 2017	Assist to modelling
VISHAY strain gauge	Vishay		Used to measure the strain produced in the experiment.
VISHAY strain gauge indicator	Vishay		Strain data acquisition.