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  1. dzhoucam

    what is the difference between wave and vibration?

    It seems both of them have the same mathmatic expression. I wonder what is the physical difference between them. Thanks.
  2. dzhoucam

    Material modelling: Drucker Prager and Crushable foam

    Hi all, I am using ABAQUS explicit to model a sandwich core material that consists of a lot of fibres aligned at small angles to the metallic faceplates. I used the continuum element to model this core. Because this material is plastic pressure dependent, I cannot use VonMises and J2 flow law...
  3. dzhoucam

    How can I continue my previous computation after a restart of computer

    Hi there Sometimes I need to turn off the computer when abaqus is computing. But I want to keep these results so that I could continue the previous computation after restar. Does anybody know how to do this? Thanks. Daowu
  4. dzhoucam

    Impact Force and Dynamic Strain Measurement

    I am doing an experiment by using a steel ball (14 mm Diameter) to impact onto the center of a simply supported circular panel with a thickness of 1.2 mm at a velocity of 2~3 m/s. I am concerned with the impact force and strain in the panel. I have finished the numerical and analytical model but...
  5. dzhoucam

    Beam To Beam Contact

    I used to encounter similar case three months ago. There are possibly two choices: 1. use explicit through the general contact as hakanturkmen said. 2. model the fibre by 3D elements rather than beam.
  6. dzhoucam

    Beam Contact Simulation

    Hi, I am trying to model two cuvred circular beam contact each other in plane. I find there are two possible choices in this problem. The first method is to use the common surface based contact method, i.e., define the beam element as beam surface and then let them contact each other. The...
  7. dzhoucam

    sound transmission loss measurement

    Thanks a lot to Highspeed. The approach you said looks very interesting. Could you tell me more about this method? I would like to know: 1. What kind of microphone or sensor do I need? Can I use the common microphone? I feel that the main cost in the measurement is microphone. 2. Could you...
  8. dzhoucam

    sound transmission loss measurement

    I want to test the sound transmission loss of one new sandwich sheet material. I checked the ISO standard test (ISO 10534-2, ASTM C384-88, ASTM E1050-98)and almost all of them require special microphones (such as impedence tube or two microphone methods), which are quite expensive (perhaps 6000...
  9. dzhoucam

    Sound absoption conficts with Sound transmission loss?

    Many thanks to Hatch and Greg! Greg makes me clear about the energy transfer in the process of sound absorption. For a barrier, however, I wonder what is the energy transfer process. My idea about the process is that when the incident sound arrives at the barrier, part of the energy is...
  10. dzhoucam

    Sound absoption conficts with Sound transmission loss?

    What is the relationship between Absorption coefficient and Sound transmission loss? I read a paper which says that the absorption ability confict with the sound transmission loss for the same material. Is it right? Why?
  11. dzhoucam

    Acoustic properities measurement of Sandwich panel

    Hi, I have a lot of questions but the following two questions are more urgent to me now. I want to measure the acoustic properties of an ultralight sandwich material(totally only 1.2mm thick). My current plan is to use the impedance tube and two microphones method(ASTM E1050) to measure the...
  12. dzhoucam

    what is the "coincidence frequency"?

    Hi, Recently, I am begining to work for a project about sound transmission loss through a sandwich panel. Many literatures says coincidency freq. is that the trace wavelength matches the free bending wave in the panel. I feel confused. What is the trace wave? What's the relation with incident...

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