Literature Review : VISCOELASTIC MATERIALS FOR PANEL VIBRATION DAMPING Hamid, M.A.K. S/V Sound Vib. 7(7), 20-26 (July 1973) 8 refs Refer to Abstract No. 73-1467

Viscoelastic Materials (VEMs) are in widespread use for vibration damping and isolation. Magnetorheological (MR) fluid devices are also increasingly used for vibration control. MR fluids are suspensions of metal particles in various carrier fluids that have properties controllable by imposition of a magnetic field, using mechanisms that suggest analogous manipulation of properties in more solid carrier or base materials. This paper describes a research effort that studied the properties of composite or compound materials that we call MR-VEM. Compared to traditional VEM, the material offers the opportunity to change properties — at a minimum, the stiffness, and to a lesser extent material damping — by application of magnetic fields. Properties can be manipulated with a DC or AC field. Magnetic design studies for MR-VEM compounds are described. The paper focuses on the experimental characterization of dynamic performance of MR-VEM devices for use in vibration isolation systems. Two properties were used as the basis for distinguishing samples: particle fill factor, that is the volume ratio of MR particles to the base VEM, and the magnitude of magnetic field applied while curing the MR-VEM elements. Applied magnetic field was also varied during testing. The compound material performance is studied through a range of experiments. Test data showing a factor of five stiffness adjustability are presented. Limitations imposed by the size of required magnetic components and by material heating are quantified and discussed. Overall, the material shows promise for applications requiring adjustability in effective stiffness. The paper concludes by considering actuation with the materials.

Download Full-text

Study of the effect of composite constrained layers in vibration damping of plates

International Journal of Applied Mechanics and Engineering ◽

10.2478/ijame-2014-0015 ◽

2014 ◽

Vol 19 (1) ◽

pp. 203-209

Author(s):

K.S.K. Sasikumar ◽

S. Selvakumar ◽

K.P. Arulshri

Keyword(s):

Composite Materials ◽

Vibration Damping ◽

Viscoelastic Materials ◽

Damping Effect ◽

Analytical Results ◽

Damping Effects ◽

Plate Type

Abstract To add damping to the system, viscoelastic materials (VEM) are added to structures, in order to enhance damping effects of the VEM, a constraining layer is attached. Due to the addition of the material on the system the fundamental characteristics of the systems are altered much. This paper analyzes the damping effect of the constraining layer on plate type structures numerically using the FEM software ANSYS. Experiments are conducted to validate the analytical results. The use of weightless composite materials as constraining layers has been analyzed. Results are compared with the conventional constraining layer materials. The results showed that composite materials give a better damping effect without much altering the fundamental characteristics

Download Full-text

Effect of Computerized Auditory Training on Speech Perception of Adults With Hearing Impairment

Perspectives on Aural Rehabilitation and Its Instrumentation ◽

10.1044/arri20.3.91 ◽

2013 ◽

Vol 20 (3) ◽

pp. 91-106 ◽

Cited By ~ 6

Author(s):

Rachel Pizarek ◽

Valeriy Shafiro ◽

Patricia McCarthy

Keyword(s):

Hearing Loss ◽

Speech Perception ◽

Literature Review ◽

Low Cost ◽

Experimental Designs ◽

Auditory Training ◽

Hearing Impairments ◽

Communicative Disorders ◽

And Training

Computerized auditory training (CAT) is a convenient, low-cost approach to improving communication of individuals with hearing loss or other communicative disorders. A number of CAT programs are being marketed to patients and audiologists. The present literature review is an examination of evidence for the effectiveness of CAT in improving speech perception in adults with hearing impairments. Six current CAT programs, used in 9 published studies, were reviewed. In all 9 studies, some benefit of CAT for speech perception was demonstrated. Although these results are encouraging, the overall quality of available evidence remains low, and many programs currently on the market have not yet been evaluated. Thus, caution is needed when selecting CAT programs for specific patients. It is hoped that future researchers will (a) examine a greater number of CAT programs using more rigorous experimental designs, (b) determine which program features and training regimens are most effective, and (c) indicate which patients may benefit from CAT the most.

Download Full-text

Taking Care of Children After Traumatic Brain Injury

Perspectives on School-Based Issues ◽

10.1044/sbi13.3.79 ◽

2012 ◽

Vol 13 (3) ◽

pp. 79-86 ◽

Cited By ~ 1

Author(s):

Julie Haarbauer-Krupa

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Literature Review ◽

School Setting ◽

Leadership Role ◽

Speech Language Pathologists ◽

Educational Information ◽

Taking Care

AbstractPurpose: The purpose of this article is to inform speech-language pathologists in the schools about issues related to the care of children with traumatic brain injury.Method: Literature review of characteristics, outcomes and issues related to the needs serving children.Results: Due to acquired changes in cognition, children with traumatic brain injury have unique needs in a school setting.Conclusions: Speech-Language Pathologists in the school can take a leadership role with taking care of children after a traumatic brain injury and coordination of medical and educational information.

Download Full-text