Experimental Investigation of Aerostatic Journal Bearings made of Carbon Fiber-Reinforced Carbon Composites

2021 ◽  
pp. 1-13
Author(s):  
Artur Schimpf ◽  
Markus Ortelt ◽  
Helge Seiler ◽  
Yandong Gu ◽  
Alexander Schwarzwälder ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Rotational Speed ◽  
Journal Bearings ◽  
Fiber Reinforced ◽  
Supply Pressure ◽  
Load Carrying ◽  
Orbit Analysis ◽  
Radial Forces ◽  
Carbon Fiber Reinforced ◽  
Static Conditions

Abstract This study describes experimental results using carbon fiber-reinforced carbon (C/C) material for porous journal bearings under static conditions. Exerted radial forces of up to 90 N, a supply pressure of up to 6 bar and a maximum rotational speed of 8000 rpm were tested. The occurrence of pneumatic hammering was not observed under these operating points. Triangulation sensors were mounted vertically and horizontally as well as in front of and behind the tested bearing. These sensors measure eccentricity and misalignment. The orbit analysis demonstrated an improvement in concentricity with an increment in the supply pressure. The layered structure of the C/C material used for the porous liner is presented. A rotational speed below 8000 rpm negligibly influenced the load-carrying capacity and the flow rate. The vertical misalignment of the shaft was determined in relation to the force-applied test bearing to the shaft. In addition, two vertically positioned sensors on the support-bearing housing were used to discern the misalignment in the absolute system. On the other hand, reducing the speed to 1000 rpm increased the concentricity error. The shaft showed no significant signs of use after the experiments. The measurements confirm the suitability of the material for porous bearings.

Surface Roughness in Drilled Carbon Fiber Reinforced Polymer (CFRP) Composite Using Diamond Coated Ball-Nose Drills

2015 ◽  
Vol 1115 ◽  
pp. 90-95 ◽  
Author(s):  
Mohamed Konneh ◽  
Sudin Izman ◽  
Atiah Abdullah Sidek ◽  
Muhammad Salahuddin Salleh
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
Feed Rate ◽  
Rotational Speed ◽  
Machining Parameters ◽  
Fiber Reinforced ◽  
Cfrp Composite ◽  
Carbon Fiber Reinforced ◽  
Coated Carbide ◽  
Twist Drills

This paper discusses an experimental investigation into the influence of machining parameters on surface roughness when drilling CFRP using 4 mm-diameter 2-fluted carbide drills coated with diamond. The experimental plan employed in this study is based on Central Composite Design technique, established considering drilling with prefixed cutting parameters in a locally prepared Carbon Fiber-Reinforced Plastic (CFRP) composite material by hand lay-up technique using diamond coated carbide twist drills. A model using multiple regression analysis between rotational speed and feed rate with the surface roughness (Ra) of the fiber reinforced laminates has been predicted for the machining conditions investigated. It has been found that the lowest surface roughness Ra (0.910 μm) was generated at rotational speed, 5062 rpm and feed rate, 180 mm/min; and the highest surface roughness Ra (4.630 μm) generated at a rotational speed of 537 rpm and feed rate of 180 mm/min.

scholarly journals Manufacturing and Performance Evaluation of Carbon Fiber–Reinforced Honeycombs

2019 ◽  
Vol 3 (1) ◽  
pp. 13 ◽  
Author(s):  
Sanjeev Rao ◽  
Jimmy Thomas ◽  
Alia Aziz ◽  
Wesley Cantwell
Keyword(s):  
Performance Evaluation ◽  
Carbon Fiber ◽  
Energy Absorption ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Fiber Reinforced ◽  
Static Compression ◽  
Epoxy Resin System ◽  
Load Carrying ◽  
Carbon Fiber Reinforced

In this work, the manufacturing characteristics and a performance evaluation of carbon fiber–reinforced epoxy honeycombs are reported. The vacuum-assisted resin transfer molding process, using a central injection point, is used to infuse a unidirectional dry slit tape with the epoxy resin system Prime 20 LV in a wax mold. The compression behavior of the manufactured honeycomb structure was evaluated by subjecting samples to quasi-static compression loading. Failure criteria for the reinforced honeycombs were developed and failure maps were constructed. These maps can be used to evaluate the reliability of the core for a prescribed loading condition. Improvements in the load-carrying capacity for the reinforced samples, as compared with unreinforced specimens, are discussed and the theoretical predictions are compared with the experimental data. The compression test results highlight a load-carrying capacity up to 26 kN (~143 MPa) for a single hexagonal cell (unit cell) and 160 kN (~170 MPa) for cores consisting of 2.5 × 3.5 cells. The failure map indicates buckling to be the predominant mode of failure at low relative densities, shifting to cell wall fracture at relative densities closer to a value of 10−1. The resulting energy absorption diagram shows a monotonic increase in energy absorption with the increasing t/l ratio of the honeycomb core cell walls.

scholarly journals Experimental Investigation on the Failure Behavior of Carbon Fiber Reinforced Polymer (CFRP) Strengthened Reinforced Concrete T-beams

2021 ◽  
Vol 23 (2) ◽  
pp. 115-122
Author(s):  
Junaedi Utomo ◽  
Muhammad Nur Khusyeni ◽  
Windu Partono ◽  
Ay Lie Han ◽  
Buntara S. Gan
Keyword(s):  
Carbon Fiber ◽  
Failure Mode ◽  
Carrying Capacity ◽  
Fiber Reinforced Polymers ◽  
Failure Behavior ◽  
Load Carrying Capacity ◽  
Fiber Reinforced ◽  
Conventional Concrete ◽  
Load Carrying ◽  
Carbon Fiber Reinforced

Carbon Fiber Reinforced Polymers (CFRP) are widely used as external concrete reinforcement. The behavior of T-beams strengthened in shear and flexure using CFRP sheets and plates was studied to analyze the load carrying capacity and failure mode as compared to conventional concrete members. The bonding response of the plate-to-concrete was investigated by comparing a specimen with a plate anchored at the far ends, one without anchoring. The sheets were in situ wet lay-up, the plate was pre-impregnated and pultruded during manufacturing. The test result suggested that this integrated strengthening method notably improved the load-carrying capacity, it was also demonstrated that anchoring had a positive but insignificant effect on the moment capacity and deformation. The influence of anchoring was noteworthy from the point of view that it shifted the failure mode from debonding to CFRP plate rupture. The most important factors influencing the behavior of CFRP strengthened beams are outlined.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

Restoring Initially Cracked Reinforced Concrete Beams utilizing Carbon Fiber Reinforced Polymer Strips

2019 ◽  
Vol 7 (1) ◽  
pp. 30-34
Author(s):  
A. Ajwad ◽  
U. Ilyas ◽  
N. Khadim ◽  
Abdullah ◽  
M.U. Rashid ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Loading Test ◽  
Control Beam ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced polymer (CFRP) strips are widely used all over the globe as a repair and strengthening material for concrete elements. This paper looks at comparison of numerous methods to rehabilitate concrete beams with the use of CFRP sheet strips. This research work consists of 4 under-reinforced, properly cured RCC beams under two point loading test. One beam was loaded till failure, which was considered the control beam for comparison. Other 3 beams were load till the appearance of initial crack, which normally occurred at third-quarters of failure load and then repaired with different ratios and design of CFRP sheet strips. Afterwards, the repaired beams were loaded again till failure and the results were compared with control beam. Deflections and ultimate load were noted for all concrete beams. It was found out the use of CFRP sheet strips did increase the maximum load bearing capacity of cracked beams, although their behavior was more brittle as compared with control beam.

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