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

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

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Page 1: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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

Madison Minsk
Page 2: 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

Page 3: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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

Page 4: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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

Page 5: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR
Page 6: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Setup

Page 7: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Experiment1. Twist wire to initiate torsional oscillation

2. Measure frequency of oscillation

3. Measure amount of damping of oscillation

Page 8: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Calculations

Internal Friction

1/20 [ln(T0/T20)]

T0

T20

Page 9: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Calculations Shear Modulus

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

=L

=r

Page 10: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Crystal Structure

•Steel is Body Centered Cubic (BCC)

•Carbon atoms occupy interstitial sites

Page 11: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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

Page 12: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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

Page 13: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR
Page 14: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

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)

Page 15: Dynamic Mechanical Properties of Metals MADISON MINSK, ANANYA GARG, RACHEL NGAI, IAN CULHANE, ERIC SPEAR

Special Thanks

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