Molecular dynamics simulation of weak bonds in carbon fiber reinforced plastic adhesive joints
TL;DR: In this article, the authors reproduce weak bonds by using a molecular dynamic equation (MDE) to reproduce the contamination at the bond line in carbon fiber-reinforced plastic (CFRP) adhesive joints.
Abstract: In carbon fiber-reinforced plastic (CFRP) adhesive joints, poor adhesion because of weak bonds may occur due to contamination at the bond line. We reproduced weak bonds by using a molecular dynamic...
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TL;DR: In this paper , the authors quantitatively compared entropy generation from a mechanical and thermal perspective via molecular dynamic simulations and experimental measurements of the polyamide 6 (PA6) material with thermal properties using differential scanning calorimetry (DSC).
Abstract: Entropy generation from a mechanical and thermal perspective are quantitatively compared via molecular dynamic (MD) simulations and mechanical and thermal experiments. The entropy generation values regarding mechanical tensile loading—which causes invisible damage—of the Polyamide 6 (PA6) material are discussed in this study. The entropy values measured mechanically and thermally in the MD simulation were similar. To verify this consistency, mechanical and thermal experiments for measuring entropy generation were conducted. The experimentally obtained mechanical entropy was slightly less than that calculated by MD simulation. The thermal capacity is estimated based on the specific heat capacity measured by differential scanning calorimetry (DSC), applying the assumed extrapolation methods. The estimated entropy generation was higher than the aforementioned values. There is a possibility that the entropy-estimating method used in this study was inappropriate, resulting in overestimations. In any case, it is verified that entropy increases with mechanical loading and material invisible damage can be qualitatively detected via thermal property measurements.
10 citations
TL;DR: In this paper , a multiscale framework for composites considering interphase based on molecular dynamics and finite element method was constructed and validated by transverse fiber bundle tensile (TFBT) experiments used to indirectly measure the interfacial normal strength in the literature.
Abstract: Conventional micromechanical experiments have difficulties in measuring the normal strength of the fiber/matrix interphase. In this paper, molecular dynamics simulations were used to construct the interphase models from molecular scale and investigate the normal and tangential strength of the fiber/matrix interphase. Furthermore, a multiscale framework for composites considering interphase based on molecular dynamics and finite element method was constructed and validated by transverse fiber bundle tensile (TFBT) experiments used to indirectly measure the interfacial normal strength in the literature. The results showed that the interfacial normal and tangential strengths were 100.9 MPa and 51.9 MPa, respectively. The prediction error of the TFBT specimens by the newly constructed multiscale framework was less than 2%, and the failure mode was the same as that observed in the experiments. The good agreement between the experimental and simulation results indicates that the method can provide a way to study the structural analysis of fiber-reinforced composites.
TL;DR: In this paper , an applied electrochemical method in the form of a chronocoulometry technique is proposed for measuring Fick's diffusion constant of a thin protective coating layer over the conductive base materials.
Abstract: An applied electrochemical method in the form of a chronocoulometry technique is proposed for measuring Fick’s diffusion constant of a thin protective coating layer over the conductive base materials. Using this method, the capacitance is monitored for a capacitor formed using the base material, an electrolyte such as aqueous NaCl, and an insulating coating layer in between. The capacitance increases when the distance between the base material and the electrolyte decreases in the diffusion of the electrolyte through the insulating coating layer. Therefore, the change in the capacitance provides a diffusion rate related to Fick’s diffusion constant. Conventional gravimetric methods require a long measurement time to reach saturation, and thin coating layers of minimal weight increment through water diffusion were demonstrated to be inadequate for the methods. However, the new electrochemical method is appropriate for thin coating layers and requires a limited duration after the onset of diffusion. Experimental for 1-mm thick PA6 films provided Fick’s diffusion constants of safer side with the new method of 15h by reflecting the heterogeneous properties of the surface, while the conventional gravimetric method in 360h provided smaller or danger-side values.
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TL;DR: The DREIDING force field as discussed by the authors uses general force constants and geometry parameters based on simple hybridization considerations rather than individual force constants or geometric parameters that depend on the particular combination of atoms involved in the bond, angle, or torsion terms.
Abstract: We report the parameters for a new generic force field, DREIDING, that we find useful for predicting structures and dynamics of organic, biological, and main-group inorganic molecules. The philosophy in DREIDING is to use general force constants and geometry parameters based on simple hybridization considerations rather than individual force constants and geometric parameters that depend on the particular combination of atoms involved in the bond, angle, or torsion terms. Thus all bond distances are derived from atomic radii, and there is only one force constant each for bonds, angles, and inversions and only six different values for torsional barriers. Parameters are defined for all possible combinations of atoms and new atoms can be added to the force field rather simply. This paper reports the parameters for the "nonmetallic" main-group elements (B, C, N, 0, F columns for the C, Si, Ge, and Sn rows) plus H and a few metals (Na, Ca, Zn, Fe). The accuracy of the DREIDING force field is tested by comparing with (i) 76 accurately determined crystal structures of organic compounds involving H, C, N, 0, F, P, S, CI, and Br, (ii) rotational barriers of a number of molecules, and (iii) relative conformational energies and barriers of a number of molecules. We find excellent results for these systems.
5,380 citations
Book•
01 Jan 1973
TL;DR: The thoroughly rewritten and enlarged Second Edition as mentioned in this paper provides hands-on assistance in the use, formulation, synthesis, processing, and handling of epoxy resins. But it does not discuss toxicity, hazards, and safe handling.
Abstract: Featuring new techniques of physicochemical analysis and broader coverage of textile applications,the thoroughly rewritten and enlarged Second Edition provides hands-on assistance inthe use, formulation, synthesis, processing, and handling of epoxy resins.Epoxy Resins, Second Edition, Revised and Expanded documents available commercialproducts, including rarer species of epoxides ... shows how to achieve qualityassurance through analytical methods ... discusses toxicity, hazards, and safe handling ...looks closely at elastomer modification of resins as well as adhesives, coatings, electrical andelectronic applications, fiber-reinforced composites, and the use of epoxy resins in thestabilization of polymers, plasticizers, and textiles ... and assists in the more efficientselection and application of epoxy resins.Complete with nearly 300 pages of tables for quick references, plus over 300 diagrams andphotographs, and more than 4,400 bibliographic references, this volume will proveindispensable to polymer, physical, and organic chemists, rheologists, materials scientists andengineers, and chemical, plastics, aerospace, automotive, and electrical and electronicsengineers.
1,325 citations
"Molecular dynamics simulation of we..." refers methods in this paper
...The chemical formula [31] of the epoxy resin is presented in (Figure 1)....
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05 Dec 2005-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, it is argued that fiber reinforced polymers, especially carbon fiber reinforced plastics can and will in the future contribute more than 50% of the structural mass of an aircraft.
Abstract: Fibrous composites have found applications in aircraft from the first flight of the Wright Brothers’ Flyer 1, in North Carolina on December 17th, 1903, to the plethora of uses now enjoyed by them on both military and civil aircraft, in addition to more exotic applications on unmanned aerial vehicles, space launchers, and satellites. Their growing use has arisen from their high specific strength and stiffness, when compared to the more conventional materials, and the ability to shape and tailor their structure to produce more aerodynamically efficient structural configurations. In this paper, it is argued that fiber reinforced polymers, especially carbon fiber reinforced plastics can and will in the future contribute more than 50% of the structural mass of an aircraft. However, affordability is the key to survival in aerospace manufacturing, whether civil or military, and therefore effort should be devoted to analysis and computational simulation of the manufacturing and assembly process as well as the simulation of the performance of the structure, since they are intimately connected.
628 citations
TL;DR: In this article, the interfacial bonding of single-walled nanotube (SWNT) reinforced epoxy composites was investigated using a combination of computational and experimental methods, which indicated that there could be an effective stress transfer from the epoxy resin to the nanotubes.
383 citations
TL;DR: It was found that the high power technique showed the greatest sensitivity to these kissing bonds at low contact pressures, however at high loads conventional longitudinal wave testing was more sensitive.
151 citations