# Exploring Materials Engineering with DIY Test Machine & Arduino

• Misc.
• Gersty
In summary, the conversation revolved around a science teacher's interest in incorporating engineering into their curriculum by building a universal testing machine for a quarter-long unit on Materials Engineering. They discussed using DIY methods and materials, as well as the use of an Arduino for data collection. Safety and the appropriate load cell size were also mentioned as important factors to consider. The teacher also questioned if the mechanical properties of a material would be the same regardless of the sample size, which would determine the size of the load cell needed for the testing machine.
Gersty
Hello there. I'm a veteran science teacher at the middle and high school level. I've taught a few years of physics and am interested in moving towards engineering.

I have looked at a number of available curricula like Project Lead the Way which require a significant investment in time and money regarding training and curriculum materials. I'm still considering this approach but in the meantime wanted to get my feet wet. I am interested in building a quarter-long unit on Materials Engineering. For this unit I want to build a low cost universal testing machine based on a 10-20 kg load cell and Arduino.

The idea is to have kids do some of the same build projects they would do in an ordinary physics class (toothpick bridge, CO2 car, windmill, crane, trebuchet, etc...) but have them test a number of materials for strength and toughness in tension, compression, and bending. They would learn to build a stress strain curve and calculate Young's Modulus in order to decide which materials to use in their build project.

1. Building the test machine. I've looked at 2-3 examples of DIY test machines on youtube already. I'm thinking about using threaded rod and rectangular steel tubing. No access to welding gear means I'll be bolting it together.

2. Is a 10kg load cell like this one https://www.sparkfun.com/products/13329 sufficient? Should I go with 20 kg? I'm new to the idea of stress and strain calculations and so I'm not sure what size my samples will need to be but I'm planning on using popsicle stick sized samples of wood, plastics, thin metal pipes and tubes, toothpicks, etc...Given that, what amount of force will I need to apply, and which load cell will be appropriate?

3. Arduino as a data collection device. I have researched the idea of using an Arduino Uno with a load cell amplifier HX711 board and have spent time online with Arduino tutorials and it seems do-able.

Thanks in advance for any input.

Last edited by a moderator:
1) You just need a load cell frame that is rigid under the highest loads to it will be subjected. Threaded rod and bolted steel will work. So will bolted / screwed / glued wood or plywood.

2) I could easily build a popsicle stick truss that would hold my weight (66 kg). I suggest at least a 100 kg load cell. If you want to do tensile tests, even that may not be enough. I suspect that a good popsicle stick could hold more than 100kg in tension. You can run some simple tests by clamping a test piece to a ceiling beam, then finding if it will hold your weight. Be careful, an overloaded load cell is permanently damaged.

3) I'm not familiar with the Arduino, the other parts you listed should work well enough for your purposes.

Bystander
Gersty said:
... have them test a number of materials for strength and toughness ...
What ever you come up with, make dang sure it will be safe for the students to use.

Safety will certainly be a top consideration.

The model I have in mind will be small. I understand that the mechanical properties of a material (toughness, strength, ductility, hardness) are the same irrespective of the size of the sample. So if I can successfully test a very small sample of a Popsicle the stress and strain curve should apply to a larger sample, correct?

If this is indeed the case, could I get away with a 20 kg load cell around which I could build a small apparatus that could be safely used in a classroom setting?

dlgoff

## 1. What is materials engineering?

Materials engineering is a field of study that involves the development, processing, and testing of materials to create new or improved products. It combines principles from chemistry, physics, and engineering to understand how materials behave and how they can be manipulated for specific purposes.

## 2. How can I explore materials engineering with a DIY test machine and Arduino?

You can explore materials engineering by building a DIY test machine, which is a device that can apply controlled forces and measure the resulting changes in a material. By using an Arduino, you can program the test machine to perform various tests on different materials and collect data for analysis.

## 3. What are the benefits of using a DIY test machine for materials engineering?

Using a DIY test machine allows for hands-on exploration and experimentation with materials, which can enhance understanding and learning. It also allows for customization and flexibility in testing different materials and properties, and can be a cost-effective alternative to purchasing expensive commercial testing equipment.

## 4. What types of materials can be tested with a DIY test machine and Arduino?

A DIY test machine and Arduino can be used to test a wide range of materials, including metals, plastics, ceramics, and composites. It can also test various properties such as strength, hardness, elasticity, and conductivity.

## 5. Do I need any prior knowledge or experience to use a DIY test machine for materials engineering?

While prior knowledge or experience in materials engineering can be helpful, it is not necessary to use a DIY test machine and Arduino. There are many online resources available that provide step-by-step instructions for building and using a test machine, and coding with Arduino is beginner-friendly. It can also be a fun and educational project for those interested in learning more about materials engineering.

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