Le Dung

9 Questions 23 Answers 0 Followers

Questions related from Le Dung

Why RMS value of a periodic signal is equal to sqrt of linear spectrum divided normalized equivalent bandwidth?

Hi everyone! I'm reading a book on noise and vibration analysis. And i knew that how to calculate a RMS value of periodic signal (x(n)) by: xRMS = sqrt(sum(XL^2(k)) / Ben) where: xRMS is RMS value...

03 March 2018 3,672 0 View

Why we need calculate equivalent noise bandwidth for windows function?

Hi everyone! Could you explain to me why we need calculate equivalent noise bandwidth (ENBW) for window functions (for example Hanning window)?

01 January 2018 698 0 View

Which book can i find formular of mass matrix of different finite element types?

Hello everyone! I have a problem, that is when i perform a finite element analysis (for example, to a beam that has high of across-section is invariant), i can easily have a formular of element...

12 December 2017 9,729 0 View

How can i use "resample" command in matlab to change Bandwidth of a measured signal ?

Hi everyone! Now, i'm reading a book "Noise and vibration analysis" by Anders Brandt. And in this book, the author wrote that we can change bandwidth of a measured signal using resample...

10 October 2017 6,615 7 View

Why is it difficult to obtain modal parameters when measure extremely light damping structures and those results is inaccurate?

Hi everyone! Now, i reading a book "modal testing: theory and practice" by Prof D.J.Ewin. And in this book, Prof D.J.Ewin wrote:" those with extremely light damping, for which measurements at...

08 August 2017 3,673 1 View

How can we calculate damping loss factor (netar) ?

Now, i'm reading the book " Modal testing theory and practice" by D.J. Ewins. And i have a problem to non-proportional structural damping. With proportional structural damping ([D] = beta*[M] +...

07 July 2017 4,933 17 View

What does locations and number of measurement points on structures depend on?

Hi. When i do a modal test on any structures. So, How many can i select number of measurement points? How can i select locations to put sensors? And, the end, what does they depend on? Thank you.

06 June 2017 7,309 2 View

How is effect of using different damping models in output of a modal analysis ?

Hi. If i do a modal analysis for a structure. And, I use different damping models (such as: viscous damping model, structural damping, and so on.). So, How is effect of using different damping...

06 June 2017 7,350 7 View

How can i calculate dynamic response of structures using mode superposition method IN FREQUENCY DOMAIN ?

Hi, I calculated dynamic response of a beam subjected to moving load using mode superposition method in time domain. And now, i want to calculate IN FREQUENCY DOMAIN. But, i don't understand mode...

04 April 2017 7,190 0 View