Thermal failure mechanism of fiber ropes when bent over sheaves

2018 ◽  
Vol 89 (7) ◽  
pp. 1215-1223
Author(s):  
Fanggang Ning ◽  
Xiaoru Li ◽  
Nick O Hear ◽  
Rong Zhou ◽  
Chuan Shi ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Thermal Damage ◽  
Synthetic Fiber ◽  
Heat Accumulation ◽  
Thermal Failure ◽  
Synthetic Fibers ◽  
Test Conditions ◽  
Bending Process ◽  
Higher Temperature ◽  
Bending Failure

Thermal damage is an important failure mechanism that affects the bending failure of fiber ropes. This is relevant because synthetic fibers often have a relatively low melting point and low thermal conductivity. In cyclic bending over sheave (CBOS), the heat generated by friction and deformation is not conducted rapidly to the external environment, and the temperature of the rope core increases quickly. This higher temperature greatly reduces the mechanical properties of the fiber, thus accelerating the final rope failure. In this paper, evidence of thermal damage in the bending process of a braided synthetic fiber rope is given. The test conditions inducing thermal damage are discussed, including stress level, bending frequency and diameter ratio. The reasons for the heat generation and the dynamic process of heat accumulation inside the rope during CBOS are also discussed. This study aims to provide theoretical and experimental guidance for the design and use of fiber rope.

Experimental Study on Profile Machining of Titanium Alloys with Superabrasive Tools

2016 ◽  
Vol 1136 ◽  
pp. 60-65
Author(s):  
Bin Jiang ◽  
Yu Can Fu ◽  
Zheng Cai Zhao ◽  
Bo Ping ◽  
Hai Ning Wang ◽  
...  
Keyword(s):  
Thermal Damage ◽  
Single Layer ◽  
Machining Process ◽  
Machining Parameters ◽  
Grinding Wheels ◽  
Grinding Forces ◽  
Cutting Depth ◽  
Higher Temperature ◽  
Fan Blade ◽  
Profile Machining

Electroplated profiled superabrasive grinding wheels which integrate both advantages of grinding and profile milling have been widely used in the machining process the wide chord hollow fan blade rabbets made of Ti-6Al-4V alloy. However, the employment of these tools has been impeded by drastic forces and thermal damage. In order to investigate the variation regularities of grinding forces and temperature with different machining parameters, experiments were carried out with single layer electroplated CBN grinding wheels. Grinding forces and temperature were measured and analyzed. Meanwhile, tool life and metallography of workpiece were studied. The results showed that higher spindle speed leads to lower forces and higher temperature. With the increase of feed rate and radial cutting depth, forces and temperature increase. Strong adherence of chips makes abrasives grits blunt which results in the increase of grinding forces after a great deal of tests. Metallographic structure of the machined workpiece is almost identical with the original sample.

The influence of natural and synthetic fibers on mixed mode I/II fracture behavior of cement concrete materials

2019 ◽  
Vol 46 (12) ◽  
pp. 1081-1089 ◽  
Author(s):  
Hossein Karimzadeh ◽  
Ali Razmi ◽  
Reza Imaninasab ◽  
Afshin Esminejad
Keyword(s):  
Fracture Toughness ◽  
Reinforced Concrete ◽  
Mixed Mode ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Synthetic Fiber ◽  
Mode I ◽  
Fiber Reinforced ◽  
Synthetic Fibers ◽  
Natural And Synthetic

This paper evaluated mixed mode I/II fracture toughness of fiber-reinforced concrete using cracked semi-circular bend (SCB) specimens subjected to three-point bending test. Additionally, a comparison was made between the experimental results and the estimations made by different theoretical criteria. Natural and synthetic fibers at various concentrations were used in this study. After producing cracks in SCB specimens at different inclination angles to induce different mixed mode loading conditions (from pure mode I to II), the fracture toughness of SCB specimens was determined. Furthermore, the compressive, splitting tensile, and flexural strength of natural and synthetic fiber-reinforced concrete were measured after 7 and 28 days of curing. While there is an increase in the aforementioned strengths with fiber content increase, 0.3% was found to be the optimum percentage regarding fracture toughness for both fibers. Also, the comparison between the experimental and theoretical results showed that generalized maximum tangential stress criterion estimated the experimental data satisfactorily.

Folding-Reliability of Flexible Electronics in Wearable Applications

2019 ◽  
Author(s):  
Pradeep Lall ◽  
Hyesoo Jang ◽  
Ben Leever ◽  
Scott Miller
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Flexible Electronics ◽  
Experimental Analysis ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Mechanism Analysis ◽  
Accelerated Test ◽  
Test Conditions

Abstract There is a growing need for flexible hybrid electronics solutions for wearable applications, in which the user may often wear electronics on body, on fabric or on skin. Electronics in wearable application may be subjected to stresses of daily motion including bending, twisting and stretching. Thus, there is need for technologies capable of flexibility, robustness and small size while being lightweight. Existing standards for focus on rigid electronics and there is scarcity of guidance for test-levels needed to assure reliability of flexible electronics. There is need for studies focused on the development of accelerated test conditions representative of field applications and the identification of failure mechanisms for test levels. In this study, experimental analysis on fatigue life of the PCB in cyclical folding load is conducted. A folding test-stand capable of replicating the stresses of daily motion in a lab-environment has been developed for the test. For the better understanding of the failure mechanism, analysis of failure modes is carried out. Consequently, it is found that fatigue life of the PCB is related to the several conditions: folding direction, moving distance, folding diameter and strain rate.

scholarly journals High-speed scanning ablation of dental hard tissues with a λ = 9.3 μm CO2 laser: adhesion, mechanical strength, heat accumulation, and peripheral thermal damage

2011 ◽  
Vol 16 (7) ◽  
pp. 071410 ◽  
Author(s):  
Daniel Nguyen ◽  
Kwang Chang ◽  
Saba Hedayatollahnajafi ◽  
Michal Staninec ◽  
Kenneth Chan ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Co2 Laser ◽  
High Speed ◽  
Thermal Damage ◽  
Heat Accumulation ◽  
Dental Hard Tissues ◽  
Hard Tissues

Influence of Montmorillonite Treated with Cetyl Trimethyl Ammonium Bromide Addition in Epoxy-Kenaf Composites

2015 ◽  
Vol 754-755 ◽  
pp. 235-239
Author(s):  
A. Zuliahani ◽  
H.D. Rozman ◽  
Abdul Rahman Rozyanty
Keyword(s):  
Cetyl Trimethyl Ammonium Bromide ◽  
Natural Fiber ◽  
Environmental Concern ◽  
Low Cost ◽  
Natural Fibers ◽  
Synthetic Fiber ◽  
Ammonium Bromide ◽  
Synthetic Fibers ◽  
Cetyl Trimethyl Ammonium ◽  
Kenaf Composites

The use of natural fiber as reinforcement in polymer composites has gained importance recently due to environmental concern and its abundance availability from agricultural crops and wood industry [1]. Many advantages offered by natural fibers over synthetic fibers include low density, greater deformability, low cost per unit volume, recyclability and biodegradability [2-3]. In addition, the mechanical properties of natural fibers such as flax, hemp, jute, sisal and kenaf are comparable with glass fiber in respect of strength and modulus [4]. Hence, many studies have been carried out to replace the synthetic fiber for composite preparation.

Preparation and Mechanical Characterization of Jute-PP and Coir-PP Bio-Composites

2015 ◽  
Vol 766-767 ◽  
pp. 122-132
Author(s):  
Tippusultan ◽  
V.N. Gaitonde
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
Natural Fibers ◽  
Weight Ratio ◽  
Synthetic Fiber ◽  
Synthetic Fibers ◽  
Fiber Loading ◽  
High Initial Cost ◽  
Full Factorial

Polymers reinforced with synthetic fibers such as glass and carbon offer advantages of high stiffness and strength to weight ratio compared to conventional materials. Despite these advantages, the prevalent use of synthetic fiber-reinforced polymer composite has a tendency to demur because of high initial cost and most importantly their adverse environmental impact. On the contrary, the increased interest in using natural fibers as reinforcement in plastics to substitute conventional synthetic fibers in automobile applications has become one of the main concerns to study the potential of using natural fibers as reinforcement for polymers. In this regard, an investigative study has been carried out to make potential utilization of natural fibers such as Jute and Coir as reinforcements, which are cheap and abundantly available in India. The objective of the present research work is to study the effects of fiber loading and particle size; fiber loading and fiber length on the mechanical properties of Jute-PP and Coir-PP bio-composites respectively. The experiments were planned as per full factorial design (FFD) and response surface methodology (RSM) based second order mathematical models of mechanical properties have been developed. Analysis of variance (ANOVA) has been employed to check the adequacy of the developed models. From the parametric analysis, it is revealed that Jute-PP bio-composites exhibit better mechanical properties when compared to Coir-PP bio-composites.

Bending failure mechanism and flexural properties of GLARE laminates with different stacking sequences

2018 ◽  
Vol 187 ◽  
pp. 354-363 ◽  
Author(s):  
Huaguan Li ◽  
Yiwei Xu ◽  
Xiaoge Hua ◽  
Cheng Liu ◽  
Jie Tao
Keyword(s):  
Failure Mechanism ◽  
Flexural Properties ◽  
Bending Failure

Effect of Natural and Synthetic Fibers and Film and Moisture Content on Stratum Corneum Hydration in an Occlusive System

1997 ◽  
Vol 67 (8) ◽  
pp. 585-592 ◽  
Author(s):  
Bruce A. Cameron ◽  
Donna M. Brown ◽  
Merry Jo Dallas ◽  
Brenda Brandt
Keyword(s):  
Moisture Content ◽  
Stratum Corneum ◽  
Natural Fiber ◽  
Fiber Type ◽  
Normal Skin ◽  
Synthetic Fiber ◽  
Hydration Level ◽  
Synthetic Fibers ◽  
Significant Difference ◽  
Natural And Synthetic

The effects of fabric made from natural and synthetic fibers and film on transepidermal water loss (tewl) from the stratum corneum (sc) were investigated using an occluded system. Sixteen fabrics differing in fiber type and construction were placed on the volar forearm of 35 female subjects in a dry state (standard moisture regain) and a wetted state. Each fabric was in place for 40 minutes before tewl was measured. There was no statistically significant difference in tewl measurements on a control skin site from the beginning to the end of the 75-minute test session in a controlled conditioned environment. Placement of dry fabrics on the skin did not significantly affect the hydration level of the sc, though all dry fabrics did increase the hydration level slightly. Wetted wool and cotton fabrics significantly hydrated the sc when levels were compared to either normal skin or skin covered by dry fabrics. Of the seven synthetic fiber fabrics tested in a wetted state, three (acrylic, ptfe, and spun nylon) significantly increased the sc hydration level. These three fabrics and the natural fiber fabrics had comparable wetted moisture content.

Application of Oil Palm Empty Fruit Bunch Fiber to Improve the Physical and Mechanical Properties of Composite Railway Brake Block Materials

2013 ◽  
Vol 651 ◽  
pp. 486-491 ◽  
Author(s):  
Triono Agus ◽  
Wiratmaja Puja Ign ◽  
Hilman Syaeful Alam ◽  
S. Rochim
Keyword(s):  
Mechanical Properties ◽  
Oil Palm ◽  
Natural Fiber ◽  
Physical And Mechanical Properties ◽  
Synthetic Fiber ◽  
Technical Requirement ◽  
Commercial Sample ◽  
Environment Friendly ◽  
Synthetic Fibers ◽  
Brake Block

One of the natural fiber considered to replace syntetic fiber is Oil Palm Empty Fruit Bunches (OPEFB) fiber which offer advantages such as environment friendly and widely available especially in indonesia . This study investigates the characteristics of railway brake block with OPEFB fibres compare to synthetic fiber. All the test results were compared to the technical requirement of PT. Kereta Api Indonesia (PT. KAI ) and evaluated using Extension Evaluation Method (EEM) to select and get the best sample. From the evaluation results using EEM, one of non commercial sample using OPEFB fiber give a better results compare to commercial sample using synthetic fibers. So it can be concluded that OPEFB fiber as reinforcement for railway brake material could improve physical and mechanical properties of the material, environment friendly and could replace synthetic fibers.

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