Viscoelastic modeling and characterization of thin-ply composite laminates

2021 ◽  
pp. 114901
Author(s):  
Milinda Yapa Hamillage ◽  
Colin Leung ◽  
Kawai Kwok
Keyword(s):  
Composite Laminates ◽  
Viscoelastic Modeling

Physical Ultrasonics of Composites

2011 ◽  
Author(s):  
Dale Chimenti ◽  
Stanislav Rokhlin ◽  
Peter Nagy
Keyword(s):  
Composite Laminates ◽  
Stiffness Matrix ◽  
Composite Plates ◽  
Anisotropic Media ◽  
Anisotropic Materials ◽  
Ultrasonic Waves ◽  
Laminated Plates ◽  
Structure Characteristic ◽  
Major Advance

Physical Ultrasonics of Composites is a rigorous introduction to the characterization of composite materials by means of ultrasonic waves. Composites are treated here not simply as uniform media, but as inhomogeneous layered anisotropic media with internal structure characteristic of composite laminates. The objective here is to concentrate on exposing the singular behavior of ultrasonic waves as they interact with layered, anisotropic materials, materials which incorporate those structural elements typical of composite laminates. This book provides a synergistic description of both modeling and experimental methods in addressing wave propagation phenomena and composite property measurements. After a brief review of basic composite mechanics, a thorough treatment of ultrasonics in anisotropic media is presented, along with composite characterization methods. The interaction of ultrasonic waves at interfaces of anisotropic materials is discussed, as are guided waves in composite plates and rods. Waves in layered media are developed from the standpoint of the "Stiffness Matrix", a major advance over the conventional, potentially unstable Transfer Matrix approach. Laminated plates are treated both with the stiffness matrix and using Floquet analysis. The important influence on the received electronic signals in ultrasonic materials characterization from transducer geometry and placement are carefully exposed in a dedicated chapter. Ultrasonic wave interactions are especially susceptible to such influences because ultrasonic transducers are seldom more than a dozen or so wavelengths in diameter. The book ends with a chapter devoted to the emerging field of air-coupled ultrasonics. This new technology has come of age with the development of purpose-built transducers and electronics and is finding ever wider applications, particularly in the characterization of composite laminates.

scholarly journals Issues on the Vibration Analysis of In-Service Laminated Glass Structures: Analytical, Experimental and Numerical Investigations on Delaminated Beams

2019 ◽  
Vol 9 (18) ◽  
pp. 3928 ◽  
Author(s):  
Chiara Bedon
Keyword(s):  
Composite Laminates ◽  
Mechanical Characterization ◽  
Dynamic Performance ◽  
Laminated Glass ◽  
Position Effects ◽  
Vibration Serviceability ◽  
Characterization Of Materials ◽  
Degradation Of Materials ◽  
Static Conditions

Load-bearing laminated glass (LG) elements take the form of simple members in buildings (i.e., columns, beams, and plates) or realize stand-alone assemblies, where glass and other traditional constructional materials can interact. Among several relevant aspects, the dynamic response of LG structures requires dedicated methods of analysis, towards the fulfilment of safe design purposes. A combination of multiple aspects must be taken into account for dynamic calculations of even simple LG elements when compared to static conditions, first of all the sensitivity of common interlayers to the imposed vibration frequency. The challenge is even more complex for the vibration serviceability assessment of in-service LG structures, where the degradation of materials and possible delamination effects could manifest, hence resulting in structural performances that can markedly differ from early-design conditions. Major uncertainties can be associated to the actual mechanical characterization of materials in use (especially the viscoelastic interlayers), as well as the contribution of restraints (as compared to ideal boundaries) and the possible degradation of the bonding layers (i.e., delaminations). All of these aspects are examined in the paper, with the support of extended analytical calculations, on-site experimental measurements, and parametric Finite Element (FE) numerical analyses. When compared to literature efforts accounting for ideal boundaries only, an analytical formulation is proposed to include the effects of flexible restraints in the dynamic performance of general (double) LG beams. Special care is also spent for the presence of possible delaminations, including size and position effects. In the latter case, existing formulations for composite laminates are preliminarily adapted to LG beams. Their reliability and accuracy is assessed with the support of test predictions and parametric FE simulations.

scholarly journals Characterization of Composite Laminates Subjected to Repeated Indentation

2014 ◽  
Vol 14 (2) ◽  
pp. 46-56
Author(s):  
M. Ashok Kumar ◽  
A.M.K. Prasad ◽  
D.V. Ravishankar ◽  
G. Giridhar
Keyword(s):  
Stainless Steel ◽  
Bearing Capacity ◽  
Fiber Orientation ◽  
Composite Laminates ◽  
Testing Machine ◽  
High Strength ◽  
Surface Damage ◽  
Load Bearing Capacity ◽  
Universal Testing

Abstract The effect of the fiber orientation in a laminate is investigated experimentally when subjected repeated quasistatic indentation. All the laminates with different fiber orientation are subjected to indentation with a stainless steel spherical indenter of diameter 8.0mm on a universal testing machine for a maximum indenter displacement of 4mm. The rate of indenter displacement was 0.5mm/minute. Different parameters like load bearing capacity, indentation diameter, area of surface damage, etc., were recorded after 4mm of indenter displacement. All the parameters were studied and compared to evaluate the laminate with high strength

Characterization of Spastic Ankle Flexors Based on Viscoelastic Modeling for Accurate Diagnosis

2019 ◽  
Vol 18 (1) ◽  
pp. 102-113 ◽  
Author(s):  
Won-Seok Shin ◽  
Handdeut Chang ◽  
Sangjoon J. Kim ◽  
Jung Kim
Keyword(s):  
Accurate Diagnosis ◽  
Viscoelastic Modeling
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