### Discussion :: Theory of machines - Section 1 (Q.No.3)

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Bheemesh said: (Aug 5, 2013) | |

Logarithmic Decrement = 2*(Pi)*Zeta/sqrt(1-zeta^2). Where zeta = Actual damping coefficient/Critical damping coefficient. |

Yas said: (Apr 26, 2014) | |

2*pi*(40/440)/sqrt(1-(40/440)^2. |

The Sark said: (Oct 5, 2014) | |

2*pi*(40/420)*(1-(40/420)^2) = 0.59. |

Gaurav said: (Mar 7, 2015) | |

Solution without calculator. Zeta = 40/420 = 0.1 (approx.). Log decrements = 2*pie*0.1/(1-0.1^2) = 2*pie*0.1 = 0.63 (approx..). |

Sarvesh Jaiswal said: (Mar 12, 2015) | |

Ld = 2*3.14*0.1/(1-0.1^2). |

Murtadha Abass said: (Jun 25, 2015) | |

2*pi*Zeta = 2*3.14*0.09 = 0.565. |

Ankit said: (Sep 6, 2015) | |

2xpixZeta/sqrt(1-Zeta^2). |

Swagat said: (May 28, 2016) | |

Thanks for all you explanation. |

Pradeep said: (Jul 18, 2016) | |

What is zeta? |

Peviks said: (Jul 20, 2016) | |

Thank you all, it great to understand the solution. |

Rohit said: (Jul 22, 2016) | |

May be Zeta is the damping coefficient. |

Ramu said: (Aug 5, 2016) | |

Zeta is damping factor or damping ratio. |

Vicky Pooraneeswar said: (Nov 7, 2016) | |

Can anyone please explain in a simple way? |

Jithin said: (Dec 8, 2016) | |

@Vicky. Just find logarithmic decrement using following equation. Logarithmic Decrement = 2 * (Pi) * Zeta/sqrt(1-zeta^2). Where zeta is ratio of Actual damping coefficient/Critical damping coefficient. |

Kareena Shah said: (Dec 17, 2016) | |

Perfect answer @Jithin. |

Mohan said: (Feb 8, 2017) | |

Good explanation. Thank you all. |

Nagamalleswarao said: (Feb 16, 2017) | |

Could you please confirm the zeta. Is this zeta is a damping factor or damping coefficient, or both are same? |

Mech Hod said: (Apr 14, 2017) | |

LD = 2 x π x 40 / sqrt(420^2-40^2) = 0.601. |

Pranay Mishra said: (May 11, 2017) | |

I am not getting this, Explain it simple way, please. |

Leela said: (Jun 13, 2017) | |

Cc=2π40/420 = 0.61. |

Prince Kumar said: (Jan 13, 2018) | |

@Pranay Mishra. Logarithmic decrement is the rate through which amplitude of free damped vibration is decreases. It is only for under damped vibration system. |

Mithun Kumar said: (Dec 22, 2018) | |

Since ln(x0/x1)= 2 * π*zeta/√ (1-zeta^2). Where zeta=actual damping coefficient/critical damping coefficient. |

Jeyaseelan said: (Dec 11, 2019) | |

first, find Damping factor = Actual damping coefficient/Critical damping coefficient then Use Damping factor formula to find Lograthemic decrement D.F=(L.D)/(4*pi*pi + L.D*L.D). Where, D.F - Damping factor L.D - Lograthemic decrement pi - 3.16 |

Ramesh said: (Jan 25, 2020) | |

THE LOGARITHMIC DECREMENT EQUATION IS; 2π(actual damping co efficient)/root of critical damping co efficient square-actual damping co efficient square. => 2 * 3.14 * 40/ √420^2 *40^2 = 80π/418 = 0.6. |

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