Research on Impact Damage of Polypropylene Fiber Mortar Based on Axial Compressive Strength

2011 ◽  
Vol 335-336 ◽  
pp. 1181-1185
Author(s):  
Yu Zhi Chen ◽  
Wei Hong Xuan ◽  
Xiao Hong Chen
Keyword(s):  
Compressive Strength ◽  
Impact Damage ◽  
Polypropylene Fiber ◽  
Drop Hammer ◽  
Damage Degree ◽  
Before And After ◽  
Axial Compressive Strength ◽  
Hammer Impact ◽  
The Right ◽  
The Impact

The method recommended by ACI Committee 544 was used in this paper. Drop hammer impact tests based on mortar specimens with different contents of polypropylene fiber were carried out. The compressive strength test is done before and after impacting. Under different drop hammer impact time, polypropylene fiber mortar specimens’ damage degree was evaluate based on compressive strength. The results show that the hammering number corresponding to the impact fracture of polypropylene fiber mortar is more than ordinary mortar that without fiber. The axial compressive strength of all specimens decreased gradually during the process of hammering, but adding the right amount of polypropylene fibers can effectively slow down the rate of strength reduction.

Ultrasonic Test Analysis of Impact Damage of Polypropylene Fiber Mortar

2012 ◽  
Vol 271-272 ◽  
pp. 324-328
Author(s):  
Xiao Hong Chen ◽  
Wei Hong Xuan ◽  
Yu Zhi Chen
Keyword(s):  
Ultrasonic Velocity ◽  
Impact Damage ◽  
Polypropylene Fiber ◽  
Ultrasonic Test ◽  
Test Analysis ◽  
Drop Hammer ◽  
Damage Degree ◽  
Hammer Impact ◽  
The Right ◽  
The Impact

The method recommended by ACI Committee 544 was used in this paper. Drop hammer impact tests based on mortar specimens with different contents of polypropylene fiber were carried out. The Ultrasonic test is done before and after impacting. Under different drop hammer impact times, polypropylene fiber mortar specimens' damage degree was evaluate based on ultrasonic velocity. The results show that the hammering number corresponding to the impact fracture of polypropylene fiber mortar is more than ordinary mortar. The ultrasonic velocity of all specimens decreased gradually during the process of hammering, but adding the right amount of polypropylene fibers can effectively slow down the rate of wave speed decline.

IMPACT RESISTANCE PROPERTIES OF KEVLAR/GLASS FIBER HYBRID COMPOSITE LAMINATES

2015 ◽  
Vol 76 (3) ◽  
Author(s):  
Norazean Shaari ◽  
Aidah Jumahat ◽  
M. Khafiz M. Razif
Keyword(s):  
Glass Fiber ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Impact Damage ◽  
Impact Resistance ◽  
Impact Behavior ◽  
Slight Reduction ◽  
Depth Of Penetration ◽  
Damage Degree ◽  
The Impact

In this paper, the impact behavior of Kevlar/glass fiber hybrid composite laminates was investigated by performing the drop weight impact test (ASTM D7136). Composite laminates were fabricated using vacuum bagging process with an epoxy matrix reinforced with twill Kevlar woven fiber and plain glass woven fiber. Four different types of composite laminates with different ratios of Kevlar to glass fiber (0:100, 20:80, 50:50 and 100:0) were manufactured. The effect of Kevlar/glass fiber content on the impact damage behavior was studied at 43J nominal impact energy. Results indicated that hybridization of Kevlar fiber to glass fiber improved the load carrying capability, energy absorbed and damage degree of composite laminates with a slight reduction in deflection. These results were further supported through the damage pattern analysis, depth of penetration and X-ray evaluation tests. Based on literature work, studies that have been done to investigate the impact behaviour of woven Kevlar/glass fiber hybrid composite laminates are very limited. Therefore, this research concentrates on the effect of Kevlar on the impact resistance properties of woven glass fibre reinforced polymer composites.

An initial investigation into the effects of the equine transeva technique (pulsating current electrotherapy) on the equine Gluteus superficialis

2021 ◽  
pp. 1-10
Author(s):  
H. Knaggs ◽  
G. Tabor ◽  
J.M. Williams
Keyword(s):  
Motor Neurons ◽  
Pretreatment Condition ◽  
Negative Change ◽  
Temporal Variables ◽  
Before And After ◽  
The Right ◽  
The Impact ◽  
Athletic Horse ◽  
Pulsating Current ◽  
Larger Sample

The equine transeva technique (ETT), is a novel electrotherapy, which utilises pulsating current electrotherapy to target sensory and motor neurons. The technique may facilitate increased circulation and correction of musculoskeletal issues and injuries, such as tendon and ligament tears and muscle atrophy. Despite the importance of understanding the impact of ETT on horses, no current scientific research exists in this area. This preliminary study investigated the effects of ETT on the musculoskeletal system of the horse, specifically within the Gluteus superficialis (GS). Using surface electromyography, muscle workload was measured in 11 sound and healthy horses of varying breeds and disciplines within the inclusion criteria. Integrated electromyography (iEMG) calculated the percentage change in maximal contractions before and after ETT treatment during one minute trials at 30 s intervals. An ANCOVA determined if these constituted significant changes (Bonferroni adjusted alpha: P≤0.02). Significant differences in muscle workload were found on the left side between pre- and post-treatment readings across trials (P≤0.02), however no significant changes occurred for the right side. The majority of horses (82%; n=9) experienced bilateral changes, with 78% of these (n=7) exhibiting a negative change in muscle workload recorded from the pretreatment condition, which may indicate muscular relaxation. The results suggest ETT may have some effect on muscle workload in the athletic horse, however further research is needed to confirm the effects observed. Future studies should include randomising the side which is treated first, a larger sample size, expansion of temporal variables and consideration of a longitudinal study to determine if these trends accrue over multiple maintenance-purposed treatments.

Low Velocity Impact on Fiber Reinforced Geocomposites

2016 ◽  
Vol 827 ◽  
pp. 145-148 ◽  
Author(s):  
Sneha Samal ◽  
David Reichmann ◽  
Iva Petrikova ◽  
Bohdana Marvalova
Keyword(s):  
Impact Damage ◽  
Acoustic Vibration ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Impact Behaviour ◽  
Reinforced Composite ◽  
Before And After ◽  
Two Parameters ◽  
The Impact

Low velocity impact strength of the fabric reinforced geocomposite has investigated in this article. Various fabrics such as carbon and E-glass were considered for reinforcement in geopolymer matrix. The primary two parameters such as low velocity, impact damage modes are explained on the E-glass and carbon based fabric geocomposite. The onset mode of damage to failure mode is examined through C-scan analysis. The quality of the composite is observed using c-scan with acoustic vibration mode of sensor before and after impact test. Then the effect of fabric and matrix on the impact behaviour is discussed. Residual strength of the composite is measured to determine post impact behaviour. It has been observed that resistance properties of E-glass reinforced composite is better than carbon fabric reinforced composite.

Experimental and simulation investigation on BVID and CAI behaviors of CFRP laminates manufactured by RTM technology

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fang Chen ◽  
Weixing Yao ◽  
Wen Jiang
Keyword(s):  
Compressive Strength ◽  
Impact Damage ◽  
Projection Area ◽  
Element Analysis ◽  
Mechanical Fracture ◽  
Content Type ◽  
Explicit Finite Element ◽  
Compression Load ◽  
Cfrp Laminates ◽  
The Impact

Purpose The purpose of this paper is to synthetically investigate the impact damage responses of carbon fiber reinforced polymer (CFRP) and its influence on the compression mechanical responses of CFRP laminates, including damage distribution, residual compressive strength and fracture morphology. Design/methodology/approach A progressive damage simulation model is developed to analyze the complicated damage responses of CFRP laminates that are manufactured by resin transfer method (RTM) technology. Based on the ABAQUS/explicit finite element analysis solver, a VUMAT code is proposed to descript the composite materials’ damage behaviors under both impact and compression load. Adopting this proposed model, the primary mechanical indicators of four groups’ 5284RTM/U3160 CFRP laminates with different stacking sequences are predicted. Moreover, impact and compression after impact tests are conducted to verify the accuracy of simulation results. Findings Both simulation and experimental results show that the impact damage with low visible detectability can significantly reduce composites’ compressive strength. For all four groups’ composite laminates, the residual strength ratio is around 35% or even lower. The kernel impact damage near the plates’ geometric center promotes the degradation process of local materials and finally leads to the early occurrence of mechanical fracture. In addition, the impact damage projection area is not sensitive to the parameters of stacking sequences, while the residual compression strength is proportional to the number of 0-degree layers within whole laminates. Originality/value This study helps to understand the effect of an impact event on CFRP laminates’ compressive bearing capacity and provides a numerical method in simulating the damage responses under both impact and compression load.

A Study on Low Velocity Impact of Woven Glass/Phenolic Composite Laminates Considering Environmental Effects

2005 ◽  
Vol 297-300 ◽  
pp. 1303-1308 ◽  
Author(s):  
Jae Hoon Kim ◽  
Duck Hoi Kim ◽  
Hu Shik Kim ◽  
Byoung Jun Park
Keyword(s):  
Compressive Strength ◽  
Environmental Effects ◽  
Impact Loading ◽  
Composite Laminates ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Internal Damage ◽  
The Impact ◽  
Phenolic Composite

The objectives of this study are to evaluate the internal damage and compressive residual strength of composite laminate by impact loading. To investigate the environmental effects, as-received and accelerated-aged glass/phenolic laminates are used. UT C-Scan is used to determine the impact damage characteristics and CAI tests are carried out to evaluate quantitatively the reduction of compressive strength by impact loading. The damage modes of the woven glass/phenolic laminates are evaluated. In the case of the accelerated-aged laminates, as aging time increases, initial failure energy and residual compressive strength decrease.

Experiment and Research on Mechanic Behavior of Concrete with Different Addition Amounts of Polypropylene Fibers

2012 ◽  
Vol 430-432 ◽  
pp. 1064-1067
Author(s):  
Yu Zhi Chen ◽  
Wei Hong Xuan ◽  
Xiao Hong Chen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Polypropylene Fiber ◽  
Polypropylene Fibers ◽  
Flexural Tensile Strength ◽  
Axial Compressive Strength ◽  
Low Dosage

The effect of the different addition amounts of polypropylene fibers on the basic mechanical properties of concrete were investigated in this paper. The results show that the flexural tensile strength of concrete changed slightly after adding low-dosage polypropylene fiber(0.04%～0.16%); Axial compressive strength and flexural tension modulus decreased, limiting flexural strain increased gradually with the amounts of fibers rising.

scholarly journals Effects of Foam Rolling Duration on Tissue Stiffness and Perfusion: A Randomized Cross-Over Trial

2021 ◽  
pp. 626-634
Author(s):  
Jan Schroeder ◽  
Jan Wilke ◽  
Karsten Hollander
Keyword(s):  
Blood Flow ◽  
Near Infrared ◽  
Tissue Perfusion ◽  
Minimal Detectable Change ◽  
Tissue Stiffness ◽  
Foam Rolling ◽  
Beneficial Effects ◽  
Before And After ◽  
The Right ◽  
The Impact

Despite its beneficial effects on flexibility and muscle soreness, there is still conflicting evidence regarding dose-response relationships and underlying mechanisms of foam rolling (FR). This study aimed to investigate the impact of different FR protocols on tissue perfusion and tissue stiffness. In a randomized crossover trial, two FR protocols (2x1 min, 2x3 min) were applied to the right anterior thigh of twenty healthy volunteers (11 females, 25 ± 4 years). Tissue perfusion (near infrared spectroscopy, NIRS) and stiffness (Tensiomyography, TMG and Myotonometry, MMT) were assessed before and after FR application. Variance analyses revealed a significant interaction of FR duration and tissue perfusion (F[1,19] = 7.098, p = 0.015). Local blood flow increased significantly from pre to post test (F[1,19] = 7.589, p = 0.013), being higher (Δ +9.7%) in the long-FR condition than in the short-FR condition (Δ +2.8%). Tissue stiffness (MMT) showed significant main effects for time (F[1,19] = 12.074, p = 0.003) and condition (F[1,19] = 7.165, p = 0.015) with decreases after short-FR (Δ -1.6%) and long-FR condition (Δ -1.9%). However, there was no time*dose-interaction (F[1,19] = 0.018, p = 0.895). No differences were found for TMG (p > 0.05). FR-induced changes failed to exceed the minimal detectable change threshold (MDC). Our data suggest that increased blood flow and altered tissue stiffness may mediate the effects of FR although statistical MDC thresholds were not achieved. Longer FR durations seem to be more beneficial for perfusion which is of interest for exercise professionals designing warm-up and cool-down regimes. Further research is needed to understand probable effects on parasympathetic outcomes representing systemic physiological responses to locally applied FR stimulations.

scholarly journals Control over the Human Body Before and After Death: The Civil Law Aspect

2020 ◽  
Vol 7 (3) ◽  
pp. 104-135
Author(s):  
L. Novoselova
Keyword(s):  
Property Rights ◽  
Human Body ◽  
Legal Status ◽  
Living Will ◽  
The Body ◽  
Human Being ◽  
Real Property ◽  
Before And After ◽  
The Right ◽  
The Impact

In this article, an attempt is made to determine the legal status of the human body (organs and tissue) both while a person is alive and after a person dies. The article discusses the points of view of various authors in relation to the possibility of considering the human body, its organs and tissue, after their separation from the body, as objects of a person’s property rights, and also as an object of a person’s non-property rights. The article argues the impossibility of qualifying the human body and the organs that were not separated from it during life as parts – and perhaps critical parts – of the existence of the total human being, as objects of real (property) rights including the rights of the persons themselves. The human body as a single object is a personal non-property benefit. The organs and tissue separated from the body may be considered objects of real rights, but on several conditions: if they were indeed separated from the body and if the person gave permission for this in a will. The specific characteristics of the legal status of the separated organs and tissue of a human being are analyzed as things (possessions) with limited turnover. The specific characteristics of the legal status of the organs and tissue separated from the body as possessions in limited turnover are reviewed as well as the impact of personal non-property rights on this status. The main focus of the article is on the legal status of the human body and the organs separated from it after death in view of the fact that transplantology and postmortem organ donation are becoming more and more widespread. This issue is analyzed in terms of the body as a whole and as it applies to the organs and tissue that are not used for transplantation. The proposal is to base our analysis on the status of the human body after death which as a rule cannot be the object of property rights. The human body is disposed of within the framework of the protection of the personal non-property rights of the deceased, including the right of physical inviolability that covers the organs and tissue separated from the body. The article characterizes the legal nature of living wills when people give instructions as to the procedure of their burial and other means of handling their body, including donation of their bodies to science. The article examines the possibility of the right of ownership to organs and tissue separated from the body after death. This right can exist if a complex legal construct is present, including a direct or assumed living will of the person. The specific characteristics of living acts concerning the possibility of after-death organ and tissue harvesting for further use, including for transplantation purposes, and the differences between such acts and last wills are determined.

scholarly journals A Study of Impact Response and Its Numerical Study of Hybrid Polypropylene Fiber-Reinforced Concrete with Different Sizes

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ninghui Liang ◽  
Ru Yan ◽  
Xinrong Liu ◽  
Peng Yang ◽  
Zuliang Zhong
Keyword(s):  
Compressive Strength ◽  
Constitutive Model ◽  
Strain Rate ◽  
Numerical Study ◽  
Polypropylene Fiber ◽  
Fiber Reinforced Concrete ◽  
Compressive Properties ◽  
Dynamic Compressive Strength ◽  
The Impact ◽  
Polypropylene Fiber Reinforced Concrete

Compressive properties of hybrid polypropylene fiber-reinforced concrete (HPFRC) with different sizes of polypropylene fibers (PPFs) under the impact load (101∼102/s) were tested by using a 74 mm diameter various cross-section split-Hopkinson pressure bar (SHPB), in which the fiber content of fine PPFs was 0.9 kg/m3 and that of coarse PPFs was 6.0 kg/m3. The effect of strain rate and PPF hybridization on the impact characteristics of HPFRC was analyzed. It is found that dynamic compressive properties, including dynamic compressive strength, dynamic compressive strength increase factor (DCF), ultimate strain, and impact toughness, increased with the increase of strain rate. Meanwhile, both fine PPFs and coarse PPFs can enhance the impact strength of concrete, and an appropriate hybridization of two sizes of PPFs in concrete was more effective than the concrete reinforced with one size of PPF. Moreover, a modified constitutive model for HPFRC was proposed based on the Holmquist–Johnson–Cook (HJC) constitutive model. Then, the numerical study of SHPB tests for HPFRC was conducted based on the modified model, which showed that the modified HJC constitutive model could well describe the dynamic stress-strain relationship of HPFRC.

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