Energy Dissipation during Vibrations of Heterogeneous Composite Structures: 3. Numerical Experiments

2019 ◽  
Vol 52 (1) ◽  
pp. 102-111
Author(s):  
L. V. Parshina ◽  
V. M. Ryabov ◽  
B. A. Yartsev
Keyword(s):  
Energy Dissipation ◽  
Composite Structures ◽  
Numerical Experiments

ONR REVIEW: ARCHITECTED COMPOSITES FOR DAMAGE TOLERANCE IN EXTREME CONDITIONS

2021 ◽  
Author(s):  
PAVANA PRABHAKAR ◽  
VINAY DAMODARAN, ◽  
ABARINATHAN PUSHPARAJ SUBRAMANIYAN
Keyword(s):  
Energy Dissipation ◽  
Composite Structures ◽  
Computational Models ◽  
Peak Load ◽  
Moisture Diffusion ◽  
Honeycomb Structure ◽  
Sandwich Composite ◽  
Extreme Conditions ◽  
Improved Performance ◽  
Damage Tolerant

The long-term goal of this ONR funded project is to facilitate the design of architected composites that play a key role in damage tolerant and resilient structures. The main emphasis is on developing new composite structures with improved performance and durability as compared to conventional structural composites. To that end, we will present our work in detail on the following within the realm of sandwich composites along with a novel Machine Learning framework for stress prediction in composites: 1) Novel recoverable sandwich composite structures: Traditional sandwich cores such as foam core or honeycomb structures are good options for enabling lightweight and stiff structures. Although, these cores are known to dissipate energy under extreme conditions such as impact loading, they experience permanent damage. Here, our goal is to design core structures that undergo substantial deformation without accumulating damage and recover their original geometric configuration after the loading is removed. In contrast to a traditional foam or honeycomb structure, we have developed a multi-layer architected core design that facilitates significant deformation beyond the initial peak load, yielding a larger energy dissipation during impact and other extreme loading scenarios. We utilize the concept of pseudo-bistability of truncated cone unit cells to achieve elastic buckling for energy dissipation and shape recovery of core structures. 2) Tailoring of sandwich composite facings: Our objective is to establish the influence of fiber architecture on moisture diffusion pathways in FRPC facings for enabling damage tolerant facing designs. To that end, we have evaluated the moisture kinetics in FRPCs by developing micromechanics based computational models within FEM. We have explained the effect of tortuous diffusion pathways that manifest within FRPCs due to internal fiber architectures. Finally, we established the relationship between tortuosity and diffusivity that can be used for studying moisture diffusion in other FRPCs.

Optimal Structural Topology Design for Energy Absorption: A Heuristic Approach

2001 ◽  
Author(s):  
Ciro A. Soto
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Porous Materials ◽  
Numerical Experiments ◽  
Topology Design ◽  
Design Rule ◽  
Structural Domain ◽  
Structural Topology ◽  
New Approach ◽  
Structural Topology Design

Abstract A new approach to design the topology for structures under crash events is presented. The approach is heuristic in essence, but numerical experiments have shown its uses in real problems. Using an interpolation between porous and solid (non-porous) materials plus a re-design rule to by-pass gradient computations the new approach is able to determine better locations of material and density in a given structural domain for kinetic energy dissipation. An example is presented to illustrate the methodology.

Supercritical Group Velocity for Dissipative Waves in Shallow Water

2012 ◽  
Author(s):  
Tae-Hwa Jung ◽  
Changhoon Lee
Keyword(s):  
Energy Dissipation ◽  
Phase Velocity ◽  
Shallow Water ◽  
Group Velocity ◽  
Water Depth ◽  
Numerical Experiments ◽  
Angular Frequency ◽  
Wave Number ◽  
Geometric Optics ◽  
Complex Valued

The group velocity for waves with energy dissipation in shallow water was investigated. In the Eulerian viewpoint, the geometric optics approach was used to get, at the first order, complex-valued wave numbers from given real-valued angular frequency, water depth, and damping coefficient. The phase velocity was obtained as the ratio of angular frequency to realvalued wave number. Then, at the second order, we obtained the energy transport equation which gives the group velocity. We also used the Lagrangian geometric optics approach which gives complex-valued angular frequencies from real-valued wave number, water depth, and damping coefficient. A noticeable thing was found that the group velocity is always greater than the phase velocity (i.e., supercritical group velocity) in the presence of energy dissipation which is opposite to the conventional theory for non-dissipative waves. The theory was proved through numerical experiments for dissipative bichromatic waves which propagate on a horizontal bed. Both the wave length and wave energy decrease for waves with energy dissipation. As a result, wave transformation such as shoaling, refraction, and diffraction are all affected by the energy dissipation. This implies that the shoaling, refraction, and diffraction coefficients for dissipative waves are different from the corresponding coefficients for non-dissipative waves. The theory was proved through numerical experiments for dissipative monochromatic waves which propagate normally or obliquely on a planar slope.

scholarly journals Experimental and Modeling Studies of Stress Wave Propagation and Energy Dissipation Mechanism in Layered Composite Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Youchun Zou ◽  
Chao Xiong ◽  
Junhui Yin ◽  
Huiyong Deng ◽  
Kaibo Cui ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Stress Wave ◽  
Composite Structures ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Stress Wave Propagation ◽  
Hopkinson Pressure Bar ◽  
Transmitted Waves ◽  
The Impact

Four composite structures (SiC/UHMWPE/TC4, SiC/TC4/UHMWPE, SiC/UHMWPE/MR/TC4, and SiC/TC4/MR/UHMWPE) were prepared using silicon carbide (SiC) ceramics, ultrahigh molecular weight polyethylene (UHMWPE), titanium alloy (TC4), and metal rubber (MR). The transmitted waves, failure forms, stress wave propagations, and energy dissipations of the composite structures were studied through Split Hopkinson Pressure Bar (SHPB) tests and numerical simulations. The results show that MR in composite structures can delay, attenuate, and smooth the stress wave, thereby reducing SiC damage. UHMWPE on the back of SiC provides cushioning for SiC, while TC4 on the back of SiC aggravates the damage of SiC. The composite structures with MR mainly dissipate the impact energy by reflecting energy, and the energy dissipation performance is better than that of composite structures without MR. A comprehensive comparison of transmitted waves, damage forms, stress wave propagations, and energy dissipations of the four composite structures shows that SiC/UHMWPE/MR/TC4 structure has the best impact resistance. Increasing the thickness of MR in the composite structures can improve the impact resistance, but there are also stress concentration and interface tensile stress.

PROGRESS ON THE DEVELOPMENT OF SHAPE-MEMORY-ALLOY METACOMPOSITES

2021 ◽  
Author(s):  
DUSAN MILOSAVLJEVIC ◽  
QIANLONG ZHANG ◽  
MARCO MOSENEDER ◽  
HONGFEI ZHU ◽  
NORA LECIS ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Composite Structures ◽  
Dynamic Properties ◽  
Research Effort ◽  
Mechanical Energy ◽  
Engineering Application ◽  
Operating Conditions ◽  
Development Effort

Shape memory alloys (SMA) have long been explored as a semi-passive approach to mechanical energy dissipation particularly, but not exclusively, for application to vibration control. More recently, the integration of SMAs in composite materials has opened the opportunity to synthesize tunable composite structures exhibiting significantly enhanced energy dissipation characteristics and a certain degree of adaptability to different operating conditions. Despite the significant progress in the development and manufacturing of SMAs over the past several decades, the cost of common Ni-based alloys has remained an important factor hindering their widespread engineering application. The long-term goal of this research effort is to model, design, and fabricate shape-memory-alloy (SMA) meta-composites employing lower volume fractions of a more affordable Cu-based alloy, while still enabling enhanced and tunable dynamic properties. This paper summarizes recent progress in the development of the meta-composite platform and focuses on aspects involving both numerical modeling and fabrication of SMA materials. On the modeling side, particular emphasis is given to assess the ability to tune the dynamic performance of continuous SMA structures by exploiting the different phases and transformations of the alloy. On the other side, the material development effort focuses on the identification of the optimal chemical composition, mechanical and heat treatment processes. A combination of numerical and experimental results is presented to illustrate capabilities and opportunities presented by this material platform.

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