Dynamic Mechanical Properties of Metals

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Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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Dynamic Mechanical Properties of Metals. Madison Minsk, Ananya Garg , Rachel Ngai, Ian Culhane , Eric Spear. Introduction. Internal Friction : the force that resists the motion of the elements in a solid while it undergoes deformation. Introduction. - PowerPoint PPT Presentation

Transcript of Dynamic Mechanical Properties of Metals

Page 1: Dynamic Mechanical Properties of Metals

Dynamic Mechanical Properties of MetalsMADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Madison Minsk
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Introduction•Internal Friction: the force that resists the motion of the elements in a solid while it undergoes deformation

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Introduction •Shear Modulus: the ratio of shear stress to the shear strain; describes the material's response to shear stress

Higher shear modulus results in less deformation from force

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Introduction•Torsion Pendulum: torsion wire is free to twist about its axis, causing the disk to rotate, associated with mechanical deformation

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Setup

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Experiment1. Twist wire to initiate torsional oscillation

2. Measure frequency of oscillation

3. Measure amount of damping of oscillation

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Calculations

Internal Friction

1/20 [ln(T0/T20)]

T0

T20

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Calculations Shear Modulus

f = frequency in Hzp = Period in secondsG = Shear ModulusI = Moment of Inertia

=L

=r

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Crystal Structure

•Steel is Body Centered Cubic (BCC)

•Carbon atoms occupy interstitial sites

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Dynamic Mechanical Analysis (DMA)

•Oscillating stress is applied, strain is measured •Frequency of oscillation or temp is altered•Output: Frequency (hz) vs Probe position (mm) graph

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Comparison of Shear Modulus and Internal Friction in Five Metals

Frequency (hz)

Internal Friction(milliN) x10^-3

Shear Modulus(Mpa) x10^5

Steel .842 8.73 5.25

Copper .631 8.46 3.01

Bronze .603 2.98 2.79

Titanium .601 2.73 2.66

Aluminum .449 25.0 1.59

0.064”

30.0625”

Dimensions

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Conclusion/Application•The shear modulus- important when materials will be subjected to shear stress

•The internal friction- important in applications like airplane engines (subjected to vibrations)

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Special Thanks

•Roy Baggerly•David Starkebaum•Davis Tran•Boeing•Tuesday Kuykendall