Mechanical properties and tensile fracture mechanism investigation of Al/Cu/Ti/Cu/Al laminated composites fabricated by rolling

An investigation into the mechanical properties of K55，N80 and P110 steels was carried out for casing-drilling technology. The obvious presence of bright facets on broken K55 Charpy V-Notch (CVN) sample surfaces was indicative of the effect of microstructure on the cleavage fracture. The appearing of bright facet surfaces of K55 was attributed to the microstructure of ferrite and pearlite. The fracture surfaces of N80 and P110 CVN samples included quasi-cleavage fracture mechanism and dimple fracture mechanism, respectively. The tensile fracture surface of all three types of casing-drilling steels included dimple fracture mechanism, both the N80 and P110 specimen show higher UTS and impact energy values compared to the K55 specimen.

Download Full-text

Effect of Hot-Alkali Treatment on the Structure Composition of Jute Fabrics and Mechanical Properties of Laminated Composites

Materials ◽

10.3390/ma12091386 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1386 ◽

Cited By ~ 9

Author(s):

Xue Wang ◽

Lulu Chang ◽

Xiaolong Shi ◽

Lihai Wang

Keyword(s):

Mechanical Properties ◽

Fracture Surface ◽

Laminated Composites ◽

Alkali Treatment ◽

Tensile Fracture ◽

Reinforced Composites ◽

Tensile Fracture Surface ◽

Pull Out ◽

Jute Fibers ◽

Jute Fabrics

In this study, jute fabrics/epoxy-laminated composites were fabricated via a simple and effective manual layering. Hot-alkali treatment was used to pretreat jute fabrics to improve their interfacial compatibility. The effects of hot-alkali treatment with five concentrations (2%, 4%, 6%, 8% and 10%) on the composition, crystallinity and surface morphology of jute fibers, were analyzed with the aids of Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and the scanning electron microscope (SEM). The mechanical properties (tensile and flexural) of laminated composites, and the morphology of the tensile fracture surface, were analyzed. The results indicated that the crystallinity index (CI) and crystallite size (CS) of the cellulose in jute fibers were improved, and there were three stages for CI and CS with the increase of alkali concentrations. Hot-alkali treatment improved the mechanical properties of laminated composites, especially for the 6% NaOH-treated jute fabric reinforced. The tensile strength, flexural strength, tensile modulus and flexural modulus of 6% NaOH-treated fabrics reinforced composites were enhanced by 37.5%, 72.3%, 23.2% and 72.2%, respectively, as compared with those of untreated fabrics reinforced composites. The fiber pull-out and the gaps of the tensile fracture surface were reduced after hot-alkali treatment.

Download Full-text

Characterization of KH-560-Modified Jute Fabric/Epoxy Laminated Composites: Surface Structure, and Thermal and Mechanical Properties

Polymers ◽

10.3390/polym11050769 ◽

2019 ◽

Vol 11 (5) ◽

pp. 769 ◽

Cited By ~ 3

Author(s):

Xue Wang ◽

Lihai Wang ◽

Wenwen Ji ◽

Quanling Hao ◽

Guanghui Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

Laminated Composites ◽

Energy Dispersive Spectrometer ◽

Flexural Modulus ◽

Tensile Modulus ◽

Crystallinity Index ◽

Xrd Analysis ◽

Tensile Fracture ◽

Jute Fibers

In this study, jute fabrics were used to reinforce epoxy resin to prepare laminated composites. KH-560 silane coupling agent modification was used to improve the interfacial compatibility between fibers and epoxy. The effects of different immersion times (0 min, 10 min, 30 min, 60 min, 90 min, and 120 min) on the jute fiber’s element content, crystal structure, and thermal stability, and the mechanical properties of laminated composites were studied. X-ray diffractometry (XRD) analysis showed that the KH-560 modification improved the crystallinity index (CI) and crystallite sizes (CS) of jute fibers. Scanning electron microscopy (SEM) analysis of the tensile fracture surfaces revealed a thick epoxy on the modified pulled fiber surfaces. Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectrometer (EDS) analysis identified the presence of silicon and C–O–Si/Si–O–Si cross-linked structures on the surface of modified jute fibers. These cross-linked structures improved the thermal stability and mechanical properties of the laminated composites. When the immersion time was 60 min, the CI, CS, tensile strength, tensile modulus, flexural strength, and flexural modulus of the modified samples were 42.39%, 3.62 nm, 34.6 ± 1.1 MPa, 2.11 ± 0.12 GPa, 83.7 ± 1.8 MPa, and 4.08 ± 0.12 GPa, respectively, which were better than that of unmodified and other modified composites.

Download Full-text

Studies on the Modification of Commercial Bisphenol-A-Based Epoxy Resin Using Different Multifunctional Epoxy Systems

Applied Mechanics ◽

10.3390/applmech2020023 ◽

2021 ◽

Vol 2 (2) ◽

pp. 419-430

Author(s):

Ankur Bajpai ◽

James R. Davidson ◽

Colin Robert

Keyword(s):

Mechanical Properties ◽

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Bisphenol A ◽

Epoxy Resin ◽

Tensile Fracture ◽

Chemical Structures ◽

Amino Phenol ◽

Epoxy Systems

The tensile fracture mechanics and thermo-mechanical properties of mixtures composed of two kinds of epoxy resins of different chemical structures and functional groups were studied. The base resin was a bi-functional epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) and the other resins were (a) distilled triglycidylether of meta-amino phenol (b) 1, 6–naphthalene di epoxy and (c) fluorene di epoxy. This research shows that a small number of multifunctional epoxy systems, both di- and tri-functional, can significantly increase tensile strength (14%) over neat DGEBA while having no negative impact on other mechanical properties including glass transition temperature and elastic modulus. In fact, when compared to unmodified DGEBA, the tri-functional epoxy shows a slight increase (5%) in glass transition temperature at 10 wt.% concentration. The enhanced crosslinking of DGEBA (90 wt.%)/distilled triglycidylether of meta-amino phenol (10 wt.%) blends may be the possible reason for the improved glass transition. Finally, the influence of strain rate, temperature and moisture were investigated for both the neat DGEBA and the best performing modified system. The neat DGEBA was steadily outperformed by its modified counterpart in every condition.

Download Full-text

Analysis of the Microstructure and Mechanical Properties of TiBw/Ti-6Al-4V Ti Matrix Composite Joint Fabricated Using TiCuNiZr Amorphous Brazing Filler Metal

Materials ◽

10.3390/ma14040875 ◽

2021 ◽

Vol 14 (4) ◽

pp. 875

Author(s):

Hao Tian ◽

Jianchao He ◽

Jinbao Hou ◽

Yanlong Lv

Keyword(s):

Mechanical Properties ◽

Base Metal ◽

Matrix Composite ◽

Room Temperature ◽

Filler Metal ◽

Ceramic Fiber ◽

Tensile Fracture ◽

Alloy Matrix ◽

Composite Joint ◽

Secondary Cracks

TiB crystal whiskers (TiBw) can be synthesized in situ in Ti alloy matrix through powder metallurgy for the preparation of a new type of ceramic fiber-reinforced Ti matrix composite (TMC) TiBw/Ti-6Al-4V. In the TiBw/Ti-6Al-4V TMC, the reinforced phase/matrix interface is clean and has superior comprehensive mechanical properties, but its machinability is degraded. Hence, the bonding of reliable materials is important. To further optimize the TiBw/Ti-6Al-4V brazing technology and determine the relationship between the microstructure and tensile property of the brazed joint, results demonstrate that the elements of brazing filler metal are under sufficient and uniform diffusion, the microstructure is the typical Widmanstätten structure, and fine granular compounds in β phase are observed. The average tensile strength of the brazing specimen is 998 MPa under room temperature, which is 97.3% of that of the base metal. During the high-temperature (400 °C) tensile process, a fracture occurred at the base metal of the highest tensile test specimen with strength reaching 689 MPa, and the tensile fracture involved a combination of intergranular and transgranular modes at both room temperature and 400 °C. The fracture surface has dimples, secondary cracks are generated by the fracture of TiB whiskers, and large holes form when whole TiB whiskers are removed. The proposed algorithm provides evidence for promoting the application of TiBw/Ti-6Al-4V TMCs in practical production.

Download Full-text

Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽

10.3390/cryst11010062 ◽

2021 ◽

Vol 11 (1) ◽

pp. 62

Author(s):

Xu Xu ◽

Zeping Zhang ◽

Wenjuan Yao

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Grain Boundaries ◽

Functional Groups ◽

Oxygen Content ◽

Tensile Fracture ◽

Hydroxyl Groups ◽

Molecular Configuration ◽

Spatial Design ◽

Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

Download Full-text