scholarly journals Effect of Exposure Temperature on the Crashworthiness of Carbon/Epoxy Composite Rectangular Tubes Under Quasi-Static Compression

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2028
Author(s):  
Tamer A. Sebaey
Keyword(s):  
Thermal Loading ◽  
Peak Load ◽  
Thermal Exposure ◽  
Static Compression ◽  
Modes Of Failure ◽  
Reinforced Plastic ◽  
Exposure Temperature ◽  
Cfrp Composite ◽  
Transportation Applications ◽  
Rectangular Tubes

The exposure of polymeric composites to thermal loading is a ubiquitous problem that leads to the degradation of mechanical properties, reducing the service life of an engineered structure, and potentially premature, catastrophic modes of failure. In the current paper, an experimental study is presented in order to investigate the effect of thermal exposure on the crushing performance of carbon fiber-reinforced plastic (CFRP) composite tubes. Specimens of rectangular tubes are subjected to thermal exposure at 90, 120, 150 and 180 °C before being crushed under quasi-static loading. The results showed a reduction in the peak load by increasing the aging temperature up to °C, which is followed by an increase in the peak load at 150 °C, due to post-curing. For the energy absorbed and the specific energy, a sharp reduction is recorded (up to 70% reduction) due to thermal aging. These results showed that the effect of thermal exposure on crashworthiness needs more attention during composites’ design, especially for transportation applications.

Biomechanics of a novel reversibly expandable dynamic craniotomy bone flap fixation plate

2020 ◽  
Vol 132 (2) ◽  
pp. 560-567 ◽  
Author(s):  
Rohit Khanna ◽  
Lisa Ferrara ◽  
Sohit Khanna
Keyword(s):  
Peak Load ◽  
Bone Flap ◽  
Intracranial Volume ◽  
Compression Tests ◽  
Static Compression ◽  
Low Profile ◽  
Flap Fixation ◽  
Tension Testing ◽  
Fixation Plate ◽  
Static Shear

OBJECTIVEBiomechanical evaluation of a novel expandable cranial fixation plate was assessed in cadavers. The dynamic craniotomy procedure uses low-profile reversibly expandable plates that allow cranial decompression by providing for intracranial volume expansion without removal of the bone flap. The plates allow reversible outward movement of the bone flap upon an increase in intracranial pressure (ICP) and also retract the bone flap and prevent it from sinking inside the cranium once the ICP normalizes.METHODSA comparative evaluation of the extent of ICP control with an increase in intracranial volume between various bone flap fixation techniques was undertaken along with testing of the expandable plate compliance. Static compression tests of the plates were performed to assess bone flap fixation and prevention of sinking. Quasi-static shear tension testing of the plates was undertaken to test the tolerance of the plates for expansion. Fatigue shear tension evaluation of the plates was undertaken to assess tolerance for repetitive expansion and contraction.RESULTSThe dynamic craniotomy provided superior control of ICP with an increase in intracranial volume compared to the hinged craniotomy and standard craniotomy techniques (p < 0.001). Static compression results revealed that the plates withstood bone flap sinkage with a mean peak load of 643.3 ± 26.1 N and a mean inward bone flap displacement of 1.92 ± 0.09 mm. Static shear tension results indicated that the plates could withstand a peak expansion of 71.6 mm. Dynamic shear tension testing of the plates with repetitive 15-mm outward expansion and retraction for a total of up to 500 cycles revealed no cracking and no failure points.CONCLUSIONSThe reversibly expandable plates provide for a low-profile bone flap fixation with rigid restriction of bone flap sinking and also enable cranial decompression with a high tolerance for repetitive expansion and contraction.

scholarly journals Nanoscopic origin of cracks in carbon fibre-reinforced plastic composites

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Masao Kimura ◽  
Toshiki Watanabe ◽  
Yasuo Takeichi ◽  
Yasuihiro Niwa
Keyword(s):  
Crack Initiation ◽  
Carbon Fibre ◽  
Crack Formation ◽  
Three Dimensional ◽  
Structural Materials ◽  
Interface Debonding ◽  
Reinforced Plastic ◽  
Safety Margins ◽  
Cfrp Composite ◽  
Carbon Fibre Reinforced Plastic

AbstractVoids and cracks can fatally degrade structural materials such as metals and ceramics but are tolerated in carbon fibre-reinforced plastic (CFRP) composites if monitored to prevent their growth to a critical size. Thus, the use of CFRPs as aeronautical structural materials requires an understanding of microscopic crack formation. However, this crack-formation mechanism remains unclear because experimental difficulties have hindered studies of relevant phenomena that occur before crack formation. Herein, we report high-resolution (~50 nm) and non-destructive three-dimensional observations of crack initiation and propagation under applied stress. This evaluation reveals that voids and cracks do not simply result from local stresses but instead occur largely through two competing nanoscale mechanisms, namely, fibre/plastic interface debonding and in-plastic crack initiation. Therefore, nanoscopic insights into these heterogeneities are essential for controlling crack initiation and determining reasonable safety margins for CFRP composite use.

Effect of Thermal Exposure on Tensile and Fatigue Properties of Clay Reinforced Nylon Nanocomposites

2015 ◽  
Vol 833 ◽  
pp. 52-55
Author(s):  
Yukiko Nakahara ◽  
Yusuke Kodama ◽  
Shi Jie Zhu ◽  
Arimitsu Usuki ◽  
Makoto Kato
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Thermal Exposure ◽  
Tensile Tests ◽  
Nylon 6 ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Oxidation Treatment ◽  
Exposure Temperature ◽  
Matrix Nanocomposite

In this paper, both nylon 6 and 2 wt% clay reinforced nylon 6 matrix nanocomposite were used for thermal exposure tests at temperatures of 80 oC and 120 oC and 150 oC, respectively. Then, the tensile tests and fatigue tests of the exposed specimens were conducted at room temperature. It was shown that the tensile strength in both nylon 6 and NCH-2 decreased with an increase in thermal exposure temperature. The brittle fracture occurred in the specimens exposed at 120 oC and 150 oC. After pre-oxidation treatment at 80 °C for 100 hours, the fatigue strength decreased 14% in nylon 6, and 8% in NCH-2. From this result, it was understood that the addition of clay in nylon 6 could suppress the decrease of fatigue strengths.

Hole Surface Quality and Damage When Drilling Unidirectional CFRP Composites

2012 ◽  
Author(s):  
Eshetu D. Eneyew ◽  
M. Ramulu
Keyword(s):  
Significant Variation ◽  
Thrust Force ◽  
Cutting Speed ◽  
Polycrystalline Diamond ◽  
Surface Damage ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Cfrp Composite ◽  
Cutting Direction

In this study, an experimental investigation on the drilling of unidirectional carbon fiber reinforced plastic (UD-CFRP) composite was conducted using polycrystalline diamond (PCD) tipped eight facet drill. The quality of the drilled hole surface was examined through surface roughness measurements and surface damage by scanning electron microscopy (SEM). It was found that, fiber pullout occurred in two specific sectors relative to the angle between the cutting direction and the fiber orientation. The thrust force was highly influenced by the feed rate than the cutting speed and it shows a significant variation throughout the rotation of the drill.

scholarly journals Influence of machining damage generated during trimming of CFRP composite on the compressive strength

2019 ◽  
Vol 54 (11) ◽  
pp. 1413-1430 ◽  
Author(s):  
N Nguyen-Dinh ◽  
C Bouvet ◽  
R Zitoune
Keyword(s):  
Surface Roughness ◽  
Mechanical Behavior ◽  
Composite Structures ◽  
Compressive Loading ◽  
Machined Surface ◽  
Reinforced Plastic ◽  
Cfrp Composite ◽  
Optical Topography ◽  
Induced Defects ◽  
Machining Damage

Machining of composite materials is a challenging task due to the heterogeneity and anisotropy of composite structures. The induced defects reduce integrity of the machined surface as well as the loading capacity of the composite structure in service. Therefore, it is necessary to quantify the damage induced during trimming and correlate the quality of the machined surface to mechanical properties. The correlation of the surface roughness criteria, widely used in literature, to the mechanical behavior raise several contradictions. For this reason, new parameters for the characterization of the machined surface are proposed and correlated to the mechanical behavior under compressive loading. In this context, carbon fiber-reinforced plastic laminates are conventionally trimmed, and the machining damage is characterized using scanning electron microscope observations, X-ray tomography, and 3D optical topography. The results reveal that crater volume and maximum depth of damage quantify the machining damage more realistic compared to the classical surface roughness criteria.

Study on Laser Cutting Carbon Fibre Reinforced Composites

2014 ◽  
Vol 800-801 ◽  
pp. 832-837
Author(s):  
Li Jun Yang ◽  
Chao Jian Hou ◽  
Wei Qiang Chen ◽  
Liang Li ◽  
Yang Wang
Keyword(s):  
Cross Section ◽  
Effective Means ◽  
Infrared Laser ◽  
Paper Analysis ◽  
Laser Parameters ◽  
Cfrp Composites ◽  
Reinforced Plastic ◽  
Cfrp Composite ◽  
Mechanism Of Interaction ◽  
The Cross

In order to solve the problem that delamination and bur will be easily produced in the process of the carbon fiber reinforced plastic (CFRP) composites, the cutting experiment of CFRP machined by pulsed Nd:YAG laser has been carried out. In the meantime, this paper investigates the mechanism of interaction between infrared laser and CFRP composite material and the quality of kerf influenced by different laser parameters and cutting directions. The study found that choosing appropriate laser parameters and cutting direction are effective means to get smaller heat affected zone (HAZ). This paper analysis the cross section morphology of kerf .The results show that the cross section does not appear stratified phenomenon and the surface is smooth, so the feasibility that infrared laser can be used to cut CFRP composites is verified.

scholarly journals Thermal Stability of YSZ Coatings Deposited by Plasma Spray–Physical Vapor Deposition

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 464 ◽  
Author(s):  
Zefei Cheng ◽  
Jiasheng Yang ◽  
Fang Shao ◽  
Xinghua Zhong ◽  
Huayu Zhao ◽  
...  
Keyword(s):  
Plasma Spray ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Thermal Exposure ◽  
Columnar Structure ◽  
Zro2 Phase ◽  
Exposure Temperature ◽  
T Phase ◽  
Thermal Stability Of ◽  
Non Line Of Sight

The plasma spray–physical vapor deposition (PS–PVD) process has received considerable attention due to its non-line of sight deposition ability, high deposition rates, and cost efficiency. Compared with electron beam–physical vapor deposition (EB–PVD), PS–PVD can also prepare thermal barrier coatings (TBCs) with columnar microstructures. In this paper, yttria-stabilized zirconia (YSZ) coatings were fabricated by PS–PVD. Results showed that the as-deposited coating presented a typical columnar structure and was mainly composed of metastable tetragonal (t′-ZrO2) phase. With thermal exposure, the initial t′ phase of YSZ evolved gradually into monoclinic (m-ZrO2) phase. Significant increase in hardness (H) and the Young’s modulus (E) of the coating was attributed to the sintering effect of the coating during the thermal exposure, dependent on exposure temperature and time. However, the values of H and E decreased in the coatings thermally treated at 1300–1500 °C for 24 h, which is mainly affected by the formation of m-ZrO2 phase.

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