Dr. Christoph Leser, MTS Systems Corporation
Dr. Christoph Leser is the product manager for monotonic testing solutions at MTS. He has 20 years of experience as a researcher, application engineer and test consultant

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Fig. 1:  a) Coupler link and b) Dimension w to be determined

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Fig. 2:  a) Actual test data (for a mild steel) and b) Simulated force - elongation curve

Transforming the Learning Experience for Materials Characterization with MTS TestSuite™ Software

Hands-on sessions with test equipment are the ideal way to expose learners to central principles of materials behavior. But maximizing each student’s time with these systems can be difficult, especially when lab resources are limited. Within a very small window of opportunity, students in a typical lab session need to work through test setup before they can observe the different modes of material deformation and rupture response. Running a good test simply takes time.

To help instructors overcome this challenge, MTS offers course curriculum that makes it easier to incorporate simulated mechanical testing inside and outside the classroom. The curriculum includes lecture notes and homework for three test types as well as MTS TestSuite™ Software with special licensing. Together, these resources enable students to witness a virtual test in the classroom, perform virtual tests in a computer lab and perform actual tests in the laboratory with greater ease and efficiency.

Developed by Dr. Christoph Leser, the curriculum was inspired by the approach test labs take to problem solving during product development. Specifically, the engineering workplace often introduces a layer of simulation between theoretical design and prototype construction. This is done for reasons familiar to university instructors: lab resources are limited but pressure to perform more tests in less time — without sacrificing accuracy — is intense.

“Using software to simulate mechanical testing can transform how materials science students learn,” Dr. Leser said. “When the identical graphical user interface is used to conduct virtual and physical materials tests, it enhances every student’s understanding of the material’s plastic yielding, stress-strain relationships, fatigue, crack growth and fracture, whether they are watching in the classroom, studying on their own or working with an actual test system.”

Establishing consistency from the lecture hall to the laboratory helps course instructors offer a more fully integrated virtual and physical curriculum. This equips students to handle all the tasks associated with test set-up, execution and data analysis more quickly, which makes the laboratory experience more efficient. An integrated curriculum also helps students understand and appreciate both the value and limitations of modeling approaches in describing material behavior.

Connecting the physical and the virtual
For a discussion on yield strength, for example, students are presented with the design of a clutch linkage. The coupler link (see Fig. 1) is a two-force member experiencing a 4.5 kN tensile force. If the force is too high, the part will yield. Students are asked to design the link by choosing an appropriate width w for a link made with a thickness t of 6 mm steel plate. To complete the design, students need to know the yield strength of the steel plate. The lab section teaches the student how to measure yield strength through measurement of the stress-strain curve and calculation of offset yield strength.

Test definition, execution and communication with the controller are done with a simulation mode within MTS TestSuite software that can be connected to a “virtual” test system and run tests on a range of “virtual” material samples. MTS provides similar resources for tension, high-cycle fatigue (HCF) and fracture mechanics testing, and all resources follow the same format. The curriculum includes instructor and student versions of test and report templates; student versions have calculations turned off so students must find these values independently.

All templates can be run virtually or with an in-house universal test system. In both cases, the experience is identical (see Fig. 2). MTS TestSuite software facilitates the transition with the use of the Python™ programming language, which has very little abstraction and makes it easier for students to move from the equation to the test program. Code is written the same way as a manual calculation would be performed. In addition, because Python is an open source language, many different sample programs and documentation are freely available.

Advantages of integration
There are several important advantages to integrating lectures, simulation and physical testing. Students gain direct experience with the material property needed to successfully complete the design exercise. Integration also provides a direct illustration of material behavior, prompting discussion of more advanced concepts, such as why materials yield, what defines ductility and why some materials are stronger than others.

In addition, students become familiar with the details of test methods, concepts, procedures and vocabulary as well as how to collect and interpret data, extract property values and identify where empirical results are used in analysis. In other words, an integrated curriculum effectively prepares students to perform real material tests. And they can do so at their own pace.

“All the aspects of running a good physical test, from specimen selection to alignment to mounting to running the test and analyzing data, take time and experience to master,” Dr. Leser said. “None of these is easy for the novice. But with an integrated curriculum, students can practice all of these steps in a simulated environment in a faster, easier way.”

Contact MTS today to learn more about using this integrated curriculum with your students, including details about licensing structures and special offers available for academic use.



MTS Systems

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