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Activity #9: Analyzing the Stress on the Trebuchet Axle

Visualizing and Describing the Engineering of Totally Trebuchet

Engineers are responsible for designing and building machines, structures, processes, and systems

that are dependable, reliable and unlikely to fail when used within the design limitations for which

they were engineered. You might consider this the next time you are a passenger on a train, plane or

automobile, or as you cross a bridge or ride an elevator.

Engineers use a variety of tools and techniques to help them create safe machines, structures,

processes, and systems. Some of these tools include:

1. A working understanding of math and science principles.

2. Mathematical models.

3. CAD models (Static and dynamic).

4. Personal experience.

5. Physical models (Like the GEARS Totally Trebuchet model).

6. Prototypes.

7. Empirical testing and analysis.

The engineers and craftsmen who designed and built medieval trebuchets depended on personal

experience, empirical testing and perhaps models and prototypes. We can make this assumption

because there is no evidence they possessed the other engineering tools and skills listed above.

Objective

x Visualize and describe how cross sectional area and material strength affect the strength of

the trebuchet axle.

x Calculate the maximum allowable stress (material yield strength) for a trebuchet axle with a

given radius and material strength.

Terms and Concepts

Use your research skills to help you develop a working understanding of these terms and concepts.

Strength of Materials Terms Software and Hardware

Tools

Engineering Terms

Compression Cross Sectional Area

Failure Calculators Deflect

Force per Unit Area COSMOSXpress Deformation

Maximum Allowable Stress Dial Calipers Dynamic Forces

PSI SolidWorks Empirical Testing

Strain Spreadsheet Software Flexural Formula

Stress GEARS-TrebStar Load

Tension Radius

Ultimate Strength Span

Yield Static Forces

Yield Strength

Sample Engineering Curriculum