scholarly journals The experiment of four-point bending behaviours of helicoidally laminated CFRPs

2019 ◽  
Vol 258 ◽  
pp. 04012
Author(s):  
Ikuma Ishizawa ◽  
Takashi Matsumoto ◽  
Kenta Kondo
Keyword(s):  
Orientation Angle ◽  
Video Camera ◽  
Metallic Materials ◽  
Characteristic Structure ◽  
Corrosion Resistant ◽  
Mantis Shrimp ◽  
Specific Strength ◽  
Four Point Bending ◽  
Angle Difference ◽  
Laminated Structures

The purpose of this study is to mitigate the brittle behaviour of CFRP. CFRP is a composite material of carbon fibre and a thermosetting resin. As a feature, it has a low density than metallic materials such as steel and aluminium, and it is excellent in specific strength, specific stiffness, and is corrosion resistant. In the civil engineering field, CFRP is expected to be utilized for durability improvement and long life achievement. However, it is necessary to be careful when using it as a primary member, because the behaviour at the time of fracture is very brittle, thereby it is necessary to set a large safety factor at the time of design. One way to achieve the purpose of the current study is to follow a biological structure, so-called biomimetics. In this study, mantis shrimp is selected. The characteristic structure of its forefoot is that chitin fibres are stacked while changing helicoidally their angles. It is said that the forefoot can withstand a thousand times the force of its own weight because of its structure. Helicoidally laminated CFRP is fabricated by processing prepreg sheets of unidirectional carbon fibres. Four laminated structures were examined in which four-point bending experiments were carried out under displacement control of 2 mm/min, and load and displacement were recorded. During the experiments, the specimens were observed until fracture with a video camera. As a result, the brittle behaviour was improved significantly as the orientation angle difference of the fibre sheets decreased.

Research Progress of the Surface Oxidation of Titanium and its Alloys

2013 ◽  
Vol 748 ◽  
pp. 188-191
Author(s):  
Hui Jun Yu
Keyword(s):  
Titanium Alloys ◽  
Biomedical Applications ◽  
Influence Factors ◽  
Surface Oxidation ◽  
Research Progress ◽  
Corrosion Resistant ◽  
Specific Strength ◽  
Existing Problems ◽  
High Specific Strength ◽  
Micro Arc Oxidation

Titanium and titanium alloys possess some attractive properties, such as excellent corrosion and erosion resistance, low densities, high specific strength and modulus, enabling them extensively used in aeronautical, marine, chemical and biomedical applications and so on. Nevertheless, Recent years, the corrosion resistance of titanium and titanium alloys is required to elevate in some fields, proper surface modification such as surface oxidation can solve the problems effectively. In this paper, the recent investigations of thermal oxidation and micro-arc oxidation to improve the corrosion resistant of titanium and its alloys are reviewed. The structures, properties and their influence factors of the coatings are analysed systematically. And the existing problems and the future prospect of the further researches is mentioned.

Flexural properties of notched carbon–aramid hybrid composite laminates

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4137-4148 ◽  
Author(s):  
TA Sebaey ◽  
Ahmed Wagih
Keyword(s):  
Hybrid Composite ◽  
Composite Laminates ◽  
High Sensitivity ◽  
Flexural Properties ◽  
Bending Tests ◽  
Specific Strength ◽  
Four Point Bending ◽  
Hybrid Laminates ◽  
Minimal Damage ◽  
Strength And Stiffness

Hybrid composite laminates are currently receiving researchers’ attention due to their specific advantages in designing laminates with improved specific strength and stiffness. One of the main disadvantages of polymeric laminated composites is their high sensitivity to notches, which cannot be avoided in design. This paper presents a comparison between two common hybridization techniques, namely sandwich and intra-ply hybridization. The study adopts experimental observations to investigate the influence of hybridization method on the flexural properties of notched carbon–aramid hybrid laminates. After four-point bending tests, the results show that the damage nature in both laminates is different. A catastrophic damage is observed for intra-ply hybrid laminates, while sandwich laminates show progressive damage. In terms of the strength, sandwich specimens show 1.3 times higher specific strength, compared to intra-ply specimens. Moreover, the bottom layers of the laminate manufactured in the sandwich fashion show minimal damage due to the high capability of the aramid/epoxy core to absorb the energy in deformation and concentrate the damage at the top layers (the compression side).

scholarly journals Approximation algorithms for tours of orientation-varying view cones

2020 ◽  
Vol 39 (4) ◽  
pp. 389-401
Author(s):  
Nikolaos Stefas ◽  
Patrick A Plonski ◽  
Volkan Isler
Keyword(s):  
Approximation Algorithm ◽  
Ground Plane ◽  
Orientation Angle ◽  
Apex Angle ◽  
Field Of View ◽  
Plane Normal ◽  
Polynomial Time Approximation Algorithm ◽  
New Variant ◽  
Angle Difference ◽  
Novel Variant

This article considers the problem of finding a shortest tour to visit viewing sets of points on a plane. Each viewing set is represented as an inverted view cone with apex angle [Formula: see text] and height [Formula: see text]. The apex of each cone is restricted to lie on the ground plane. Its orientation angle (tilt) [Formula: see text] is the angle difference between the cone bisector and the ground plane normal. This is a novel variant of the 3D Traveling Salesman Problem with Neighborhoods (TSPN) called Cone-TSPN. One application of Cone-TSPN is to compute a trajectory to observe a given set of locations with a camera: for each location, we can generate a set of cones whose apex and orientation angles [Formula: see text] and [Formula: see text] correspond to the camera’s field of view and tilt. The height of each cone [Formula: see text] corresponds to the desired resolution. Recently, Plonski and Isler presented an approximation algorithm for Cone-TSPN for the case where all cones have a uniform orientation angle of [Formula: see text]. We study a new variant of Cone-TSPN where we relax this constraint and allow the cones to have non-uniform orientations. We call this problem Tilted Cone-TSPN and present a polynomial-time approximation algorithm with ratio [Formula: see text], where [Formula: see text] is the set of all cone heights. We demonstrate through simulations that our algorithm can be implemented in a practical way and that by exploiting the structure of the cones we can achieve shorter tours. Finally, we present experimental results from various agriculture applications that show the benefit of considering view angles for path planning.

On the Flow and Creep Strength of Power Law Materials Containing Rigid Reinforcements

1990 ◽  
Vol 194 ◽  
Author(s):  
Ming Y. He
Keyword(s):  
Power Law ◽  
Creep Strength ◽  
Ceramic Materials ◽  
Al Alloys ◽  
Metallic Materials ◽  
Flow Properties ◽  
Flow Strength ◽  
Specific Strength ◽  
High Specific Strength ◽  
Properties Of Materials

AbstractInvestigation of the flow properties of materials containing rigid reinforcements has been prompted by various technological challenges concerned with high specific strength composites. The materials of interest range from metallic materials such as Al alloys, to ceramic materials such as Si3N4 and also include the intermetallics: TiAl and MoSi2. The reinforcements are typically A12O3 and SiC. The strengths of interest may be the flow strength at ambient temperature or the creep strength. The present analysis constitutes an attempt to provide estimates of either the flow or creep strength for matrices that exhibit power law deformation.

Axial Collapse Characteristics of Aluminum/CFRP Compound Circular Tubes

2005 ◽  
Vol 297-300 ◽  
pp. 166-171 ◽  
Author(s):  
Cheon Seok Cha ◽  
Kil Sung Lee ◽  
Seung Hoon Kim ◽  
Jin Oh Chung ◽  
In Young Yang
Keyword(s):  
Fiber Orientation ◽  
Brittle Failure ◽  
Orientation Angle ◽  
Axial Loading ◽  
Absorbed Energy ◽  
Aluminum Tube ◽  
Specific Strength ◽  
Collapse Characteristics ◽  
Aluminum Tubes ◽  
Fiber Orientation Angle

Aluminum or CFRP (Carbon Fiber Reinforced Plastics) tube subjected to axial loading sustains load, and absorbs energy during axial collapse. The aluminum tube absorbs energy by stable plastic deformation, while the CFRP tube with higher specific strength and stiffness than those of the aluminum tube absorbs energy by unstable brittle failure. To achieve a synergy effect by combining the two members, aluminum/CFRP compound tubes were manufactured, which are composed of aluminum tubes wrapped with CFRP outside aluminum tubes with different fiber orientation angle of CFRP and number of plies. The axial quasi-static collapse tests were performed for the tubes. The collapse characteristics of the tubes were compared with those of respective aluminum tube and CFRP circular tube. Test results showed that the collapse of the aluminum/CFRP tubes complemented unstable brittle failure of the CFRP tube due to the ductile characteristics of the inner aluminum tube. The collapse modes and the absorbed energy were influenced by the fiber orientation angle of CFRP and the number of plies. The absorbed energy per unit mass, which is in the light-weigh aspect, was higher in the aluminum/CFRP compound tube than in the aluminum tube or the CFRP tube alone.

Hardening Mechanism through Phase Separation of Beta Ti-35Nb-7Zr-5Ta and Ti-35Nb-7Ta Alloys

2012 ◽  
Vol 1487 ◽  
Author(s):  
C. R. M. Afonso ◽  
P. L. Ferrandini ◽  
R. Caram
Keyword(s):  
Phase Separation ◽  
Biomedical Applications ◽  
Metallic Materials ◽  
High Corrosion Resistance ◽  
Coherent Interface ◽  
Hardening Mechanism ◽  
Specific Strength ◽  
Β Phase ◽  
High Specific Strength ◽  
Low Elastic Modulus

AbstractThe β titanium alloys are highly attractive metallic materials for biomedical applications due to their high specific strength, high corrosion resistance and excellent biocompatibility, including low elastic modulus. The aim of this work is the evaluation of hardening mechanism through phase separation in β Ti-35Nb-7Zr-5Ta (TNZT) and Ti-35Nb-7Ta (TNT) alloys. Ingots (50 g) of TNZT and TNT alloys were arc-furnace melted in Ar(g)atmosphere. XRD using synchrotron radiation together with TEM and HRTEM analysis showed the coexistence of two separated phases (β and β’) with similar crystalline structures and slightly different lattice parameters in TNZT and TNT alloys. It was detected a heterogeneous microstructure alternating nanosized dark and bright regions (∼10 nm) with different compositions (Nb-rich β and Ta-Zr-rich β’).In aged condition (400ºC/4h), TNZT and TNT alloys undergoes coherent spinodal decomposition of β phase into two solid solution phases with coherent interface, different compositions and elastic strain associated with nanometric domains of Nb-rich β and Ta-(Zr)-rich β’ phases.

The Impact Collapse Characteristics of Al/CFRP Members for Light-Weight

2006 ◽  
Vol 321-323 ◽  
pp. 881-884
Author(s):  
In Young Yang ◽  
Kil Sung Lee ◽  
Cheon Seok Cha
Keyword(s):  
Energy Absorption ◽  
Fiber Orientation ◽  
Brittle Failure ◽  
Orientation Angle ◽  
Specific Strength ◽  
Reinforced Plastics ◽  
Collapse Characteristics ◽  
Fiber Orientation Angle ◽  
Strength And Stiffness ◽  
The Impact

In this study, the impact collapse tests were performed to investigate collapse characteristics of Al/CFRP member which were composed of aluminum members wrapped with CFRP (Carbon Fiber Reinforced Plastics) outside aluminum member. Aluminum members absorb energy by stable plastic deformation, while CFRP members absorb energy by unstable brittle failure with higher specific strength and stiffness than those in the aluminum member. In an attempt to achieve a synergy effect by combing the two members, Al/CFRP members were manufactured and impact collapse tests were performed for the members. Based on the respective collapse characteristics of aluminum and CFRP members, the collapse modes and energy absorption capability were analyzed for Al/CFRP member which have different fiber orientation angle of CFRP. Test results showed that the collapse of the Al/CFRP member complemented unstable brittle failure of the CFRP member due to ductile nature of the inner aluminum member and the fiber orientation angle of Al/CFRP members influence energy absorption capability and collapse mode.

Potential Composite Structures for NASA Future Launch Vehicles and Crew Spacecraft

2011 ◽  
Vol 410 ◽  
pp. 17-17
Author(s):  
John P. Gyekenyesi
Keyword(s):  
Composite Structures ◽  
Space Shuttle ◽  
Lessons Learned ◽  
Ceramic Fiber ◽  
Metallic Materials ◽  
Launch Vehicles ◽  
Specific Strength ◽  
Energy Applications ◽  
Carbon Ceramic ◽  
Engineering Practices

Because of their well known specific strength, stiffness and excellent durability properties, advanced composites are being considered for primary structures in launch vehicles, crew modules and various components for increased performance and cost reduction. Therefore, it is prudent and beneficial to review the engineering practices and lessons learned in connection with their use in related aeronautic and energy applications, where they are already replacing formerly used metallic materials. Examples of composite components will be shown for the reusable space shuttle orbiter where a number of different composite systems performed very satisfactorily. In addition, very large potential polymer composite designs for future launch vehicles will be discussed. Among them are payload shrouds, interstage structures and the typical intertank shell, wherein thrust booster rockets are often attached between the core stage propellant and oxidizer tanks. In addition, cryogenic propellant composite vessels of different sizes and shapes were fabricated with mostly excellent results, although some spectacular failures were also observed. High pressure composite overwrapped vessels, with and without metallic liners, will be described. Compared to widely used metallic materials, some special features of composites are listed. Relevant design allowables, depending on mission requirements, will be summarized and currently used design practice for aircraft and spacecraft in the US will be reviewed. The well-known “building - block” approach, which is often used to design military as well as civilian aircraft, will be summarized. Some of the most popular micromechanics and macromechanics computer programs used to analyze composite structures, especially with finite elements, will be listed. Although very high temperature composites like carbon/carbon, carbon/ceramic and ceramic/ceramic fiber/matrix systems are also selectively used, the focus in our discussion will be on advanced polymer matrix, carbon/glass fiber systems.

Influence of Misch Metal Addition and Deformation Processes on Microstructure and Mechanical Properties in AZ61 Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 1707-1712 ◽  
Author(s):  
Suk Bong Kang ◽  
Hyoung Wook Kim ◽  
Sang Su Jeong ◽  
Jae Woon Kim
Keyword(s):  
Magnesium Alloys ◽  
Metallic Materials ◽  
Specific Strength ◽  
High Specific Strength ◽  
Misch Metal ◽  
Deformation Processes ◽  
Structural Parts ◽  
Strength And Stiffness ◽  
Metal Addition ◽  
Hexagonal Closed Packed

Magnesium alloys have been known as the best lightweight metallic materials for various applications of electronic equipments and automobile parts due to high specific strength and stiffness. The needs for wrought magnesium alloys have been increased for the application to structural parts in the form of sheets and bars. However, magnesium has a hexagonal closed-packed (HCP) crystal structure with a limited number of operative slip systems at room temperature, and its formability is restricted to mild deformation. The improvement of the formability of magnesium sheets for real applications is important. In order to increase formability of magnesium sheets at elevated temperature, one promising way is a grain refinement.

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