Impact Fatigue Test Apparatus for 3D Printed Samples

The Problem:3D printing is rapidly becoming a viable method to produce components for manufacturing in a variety of different materials. The ability to produce a part that requires little to no additional processing saves time and money for manufacturers. However, in certain materials, there is currently no method available for determining the service life of 3D printed parts.

The Solution:Research is currently being conducted by Dr. Owen Kingstedt at the University of Utah to develop methods of determining the impact fatigue life of materials used in additive manufacturing. The objective of this design team is to create a fully automated test apparatus that can simulate repeated impacts to an object at a precise velocity. These impacts simulate stresses that components may experience through the course of their service life. Not unlike the landing forces of an aircraft or the force of an automobile accident.

Precision ControlThe force of impact is directly related to the mass of an object and the speed at which it travels. The device needed to be designed to repeatedly deliver a mass into a sample at a controlled velocity. To accomplish this the team employed the use of digital sensors and controls that were monitored and set by the use of LabVIEW software.

Class I Laser Range SensorUsed by LabVIEW to determine the distance the piston-cylinder has traveled

Diffuse Proximity SensorLabVIEW’s program uses the analog signal from this sensor to time the moment the mass passes it’s line of sight. The change in distance divide by the change in time

calculates the velocity of the mass.

Digital Air-Gas RegulatorA low current analog signal is sent from LabVIEW that sets the system pressure used to drive the piston-cylinder. This compresses the spring, providing the force to drive the impactor into the sample.

Pressure SensorThe analog signal from this sensor is read by LabVIEW and tells the program when the system has reached the desired pressure. System pressure relates the amount of spring travel required to load the spring.

Finite Element Analysis

Static loading fatigue models were used as a baseline to design the components restraining the test sample. Computer generated stress models of the sample and critical components of the system were done with the use of ANSYS.

Results from FE analysis were used to calculate design parameters such as, material selection, component dimension, spring constant, fatigue life, and estimated number of cycles.

Fully Automated Control Circuit DesignEvery component is wired to the LabVIEW’s

compact digital acquisition (DAQ) chassis which houses modules that convert analog voltage and current signals into data. This data is then used by LabVIEW to determine distance, pressure, speed and number of completed cycles of the system. LabVIEW also communicates to control devices that open and close valves or set the system’s pressure.

LabVIEW Virtual Instrument DesignThis software uses visual programming methods to create virtual instruments that collect data and control hardware in an automated system. Like any program, a plan of attack is required to help engineers develop a program to perform the desired tasks. Algorithms and block diagrams are two such methods that help engineers and programmers visualize the steps their program should take to perform these tasks.

Technical Advisor: Owen Kingstedt Ph. D., Aerospace Engineering, University of Illinois at Urbana-Champaign

Design Team: Arif Amin, Brandon Corwin, Hiren Suthar, Nor Zaki