Tiny Fibers Research Articles

Effect of Fatigue Crack Propagation in the Shape Memory Alloy Fiber Reinforced Smart Composite

In this paper, the TiNi fiber reinforced / Polycarbonate(PC) composite material is developed, and its properties is studied. Conducting fatigue experiments, shape memory effect of the material for preventing fatigue crack growth are investigated. The fatigue behavior and crack propagation are observed under increasing temperature with a SEM servo-pulser, which is a fatigue testing instrument with scanning electron microscope. As the results, the effectiveness of fatigue resistance is confirmed. The shape memory effect and expansion behavior of the matrix caused by increasing temperature create the effect of the fatigue crack propagation control. It is verified that the controlling of fatigue crack growth is attributed to the compressive stress field in the matrix which is caused by shrinkage of the TiNi fibers above austenitic finishing temperature (Af).

Self-Detection of Temperature in TiNi Fiber Reinforced Smart Composite Materials

The method of generating the most practicable shape recovery force in smart composite materials which embedded shape-memory alloy (SMA) fiber under the resin matrix is electric heating. However, because the calorie for the heating of the resin matrix increases in the low temperature environment, it is necessary to control the electric heating corresponding to an ambient temperature to obtaining a steady shape recovery force. Then, the method of self-detecting the temperature without using a special temperature sensor by measuring the electrical resistance of the SMA fiber in the composite material was examined.

Elucidating the Biosynthesis of Chitin Filaments and their Configuration with Specific Proteins and Electron Microscopy

To deepen the knowledge of chitin synthesis, a yeast mutant has been used as a model. Purified chitin synthase I-containing vesicles (chitosomes) with a diameter of 85 to 120 nm are identified by electron microscopy to eject tiny fibers upon addition of UDP-N-acetylglucosamine. The filigree of extruded filaments fused gradually into a large three-dimensional network, which is degradable by a chitinase. The network is targeted and restructured by the Streptomyces chitin-binding protein CHB1, which has a very high affinity only for alpha-chitin. Within the chitosomes, filaments are found to be highly condensed within consecutive oval fibroids, which are specifically targeted by the alpha-chitin-binding protein. The presented data give new insights to the generation of chitin filaments with an antiparallel (alpha) configuration. [image: see text]

OS16-2-1 Evaluation of Joule heating and cooling speed factor in TiNi fiber reinforced smart composites

Efficient Joule heating and cooling are necessary for the repetition use of the shape recovery force of shape-memory alloy (SMA) fiber reinforced smart composite materials. Then, the main factor on Joule heating and the cooling speed in the SMA single fiber and the SMA fiber reinforced smart composite materials was experimentally evaluated in this research. The effect of an environmental temperature, the forced convection, and the free convection was evaluated as the main factor in the SMA single fiber, and the structural condition of the matrix was evaluated in the composite material. The significant point in the temperature characteristic of the SMA electrical resistance was used as a marker of heating and the cooling progress. As a result, the cooling speed confirmed the decrease though joule heating speed rose by the rise of the operation environment temperature. Moreover, Joule heating and the cooling characteristic change greatly in the SMA single fiber depending on the air cooling condition. In the composite material, the result of the large change depending on the heat transmission characteristic and the structural condition of the matrix material was obtained.

Additional Muscle in Idiopathic Club Foot

During the dissection of seven club feet of foetuses, aborted between the 25th and 37th week of gestation, an additional muscle bundle was found in a right foot. This muscle arose from both heads of the gastrocnemius muscle, continued downwards onto the posterior surface of the soleus, crossed the calcaneal tendon and assumed a position on the lateral side of the calcaneal tendon. The muscle's tendon was fixed just laterally to the calcaneal tendon in the calcaneal tuberosity with some tiny fibres branching off into the superior fibular retinaculum.

Temperature measurement based on radialization power for micro-hotplate

A novel method to measure the temperature on the surface of micro-hotplate was presented. The tiny fiber probe and the optical power meter were employed to measure the sample radialization power. By means of comparing the relationship between the radialization power and the temperature, sample surface temperature can be discerned accurately. Such an approach has provided more accuracy than traditional temperature measurements. The experimental result based on this method is quite similar to that of simulation by the finite element analysis (FEA) software of Ansys in theory. This measurement is very useful for measuring temperature for these micro samples prone to be untouchable.

225 TiNiファイバ強化スマート複合材料における温度の自己検出(OS9(4) 形状記憶合金の特性と応用)

225 TiNiファイバ強化スマート複合材料における温度の自己検出(OS9(4) 形状記憶合金の特性と応用)

Influence of stacking angle of carbon fibers on fracture behavior of TiNi fiber impregnated CFRP composites

TiNi/CFRP composites have been fabricated by hot-pressing at a temperature of 180 °C. The CFRP layers were stacked with the carbon fibers at angles of 0°, 30°, 60° or 90° relative to the tensile direction. The fracture behavior was studied using notched specimens, which act as one-dimensional AE sources during tensile testing, to determine the fracture mode of the composites. Detection of strong Lamb waves shows that fracture in TiNi/CFRP composites with a 0° stacking configuration is mostly due to fiber breakage, which accounts for the high tensile strength of this configuration. In contrast, specimens with high stacking angles mainly fail by matrix cracking, with the production of weak Lamb waves, resulting in lower tensile strengths.

Control Effect on Fatigue Crack Propagation of TiNi Fiber Reinforced PMMA Composites

In this paper, the TiNi fiber reinforced/PMMA (Poly methyl methacrylate) composite is developed, and its effectiveness of controlling fatigue crack growth is studied. The TiNi fiber reinforced/PMMA composite’s mechanical property enhancement and deformation resistance are also studied. The fatigue behavior and crack propagation are observed with a SEM servo-pulser (fatigue testing instrument with scanning electron microscope) while increasing temperature. As the results, it is confirmed that the fatigue life and resistance are improved. How the shape memory effect and expansion behavior of the matrix caused by temperature increasing affect the fatigue crack propagation control is examined. It is verified that the control of fatigue crack growth is attributed to the compressive stress field in the matrix due to shrinkage of the TiNi fibers above austenitic finishing temperature (Af).

Mechanical properties of TiNi fiber impregnated CFRP composites

TiNi fiber impregnated CFRP composites have been fabricated by hot-pressing at a temperature of 180 °C. The host material (CFRP) layers were stacked with the carbon fibers at angles of 0°, 30°, 60° or 90° relative to the tensile direction. The tensile strengths and Young's moduli of the composites are found to depend strongly on the stacking angle of the carbon fibers. Their values decrease as the stacking angle increases from 30° to 90°. Pores and/or voids are found to congregate near the embedded TiNi fibers and their amounts increase proportionally with the stacking angle of the carbon fibers. The effect of strengthening by stacking angle of carbon fibers was studied by an AE technique during tensile testing.

Thermomechanical response of TiNi fiber-impregnated CFRP composites

The focus of this work is the thermomechanical characterization of pre-strained TiNi fiber impregnated CFRP composites. TiNi/CFRP composites were fabricated by hot-pressing at a temperature of 180 °C. The compressive recovery force induced by thermomechanical actuation of TiNi fibers depends on the pre-strained level. The shrinkage strain due to the thermomechanical response of the composites increased with increasing pre-strain level and number of impregnated TiNi fibers. Transverse cracks which formed at 90 ° to the CFRP layers under tensile loading could be healed by the compressive recovery force introduced by pre-strained TiNi fibers when electrically heated.

Adhesive strength between TiNi fibers embedded in CFRP composites

The effect of treating the surface of TiNi fiber by acid etching on the interfacial adhesive strength between the TiNi fiber and the CFRP matrix is investigated. For acid etching of the TiNi fiber, acid solutions of 36% HCl, 15% HNO 3, 97% H 2SO 4, and 3% HF+15% HNO 3 were used. The composites were fabricated by curing at 180 °C for 2 h using hot-pressing. The interfacial adhesive strength between the embedded TiNi fiber and the CFRP matrix was evaluated by a pullout test. It was found that surface treatment of the TiNi fiber by acid etching improved interfacial adhesive strength.

Control of Shape Recovery Force in TiNi Fiber Reinforced Composite

Control of Shape Recovery Force in TiNi Fiber Reinforced Composite

Effect of Crack Closure in Shape Memory Alloy TiNi Fiber Reinforced/CFRP Composite

Effect of Crack Closure in Shape Memory Alloy TiNi Fiber Reinforced/CFRP Composite

TiNi/Al기 형상기억복합재료의 강도평가를 위한 전문가시스템의 개발

In this paper, a study on the development of expert system for Al matrix composite with shape memory alloy fiber is performed to evaluate termomechanical behavior and mechanical properties. Expert system is very useful computer-based analysis system designed to make analysis technique and knowledge conveniently available to a lot of fabricable condition. In the developed system, it is possible to predict termomechanical behavior and mechanical properties for other composite with shape memory alloy fiber. The smartness of the shape memory alloy is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when heated after being prestrained. For finite element analysis, an analytical model is assumed two dimensional axisymmetric model compared of one fiber and the matrix. To evaluate the strength of composite using FEM, the concept of smart composite was simulated on computer. Thus, in this paper, the FEA was carried out at two critical temperature conditions; room temperature and high temperature(363K). The finite element analysis result was compared with the test result for the analysis validity.<br/>

Control Effect on Fatigue Crack Propagation of TiNi Fiber Reinforced / Polycarbonate Composite Material

In this paper, the TiNi fiber reinforced / PC composite material was developed, and then control of the fatigue crack growth due to the shape memory effect was studied. Enhancement of mechanical properties and resistance of deformation of the TiNi fiber reinforced / PC composite were investigated by fatigue experiments. The fatigue behavior and crack propagation were in-situ observed with a SEM servo-pulser (fatigue testing instrument with scanning electron microscope) while increasing temperature. As the results, the fatigue life was improved, and the effectiveness of fatigue resistance was confirmed. The shape memory effect and expansion behavior of the matrix caused by temperature increasing examined the effect of the fatigue crack propagation control. It was verified that the control of fatigue crack growth is attributed to the compressive stress field in the matrix due to shrinkage of the TiNi fibers above austenitic finishing temperature (Af).

Fatigue crack propagation and local crack-tip strain behavior in TiNi shape memory fiber reinforced composite

Active enhancement of fatigue resistance of shape memory alloy TiNi fiber reinforced epoxy matrix composite was studied in this paper. Fatigue crack propagation behaviors were investigated by using fine-grid method, which was engraved on the epoxy surface by photo-etching. The effects of prestrain in TiNi fiber on fatigue crack development and suppression in the local domain region around the embedded TiNi fibers were investigated in detail. The retardation of fatigue crack propagation is attributed mainly to the compressive stress in the matrix caused by shrinkage of the pre-strained TiNi fibers above A f temperature. The local crack-retardation at the interface region very near the TiNi fiber is experimentally 0 confirmed by the change of local crack-tip strain behavior. Crack-tip strain hysteresis in one load cycle indicates that the compressive stress induced in the matrix and the following crack closure play key roles to suppress the crack-tip stress intensity and fatigue crack propagation. Fractographic study verified that suppression by shape memory alloy (SMA) fiber improves fatigue fracture toughness.

トラス橋構造モデルの制振効果(OS10-1 材料特性・制振効果,OS10 インテリジェント材料の機能・特性および評価)

トラス橋構造モデルの制振効果(OS10-1 材料特性・制振効果,OS10 インテリジェント材料の機能・特性および評価)

Shape Recovery Force of TiNi Fiber Reinforced Composite by Electric Heating

The shape-memory effect of shape-memory alloy (SMA) and the character of the super elasticity are common and effective in today's usage. This paper advances these characteristics by discussing the research of an intelligent composite which functions in a wide-ranging ambient conditions TiNi type SMA fiber was used in the experiment and the embedded test piece was used in a polymer matrix. The influence factor of the actuator function by the shape-memory effect was evaluated in real-time by measuring the length change of the test piece during electric resistance heating. Using composite materials with the electric heating method resulted in a quantitative understanding of the primary factor influencing the shape recovery force. It has been understood that the shape recovery force is greatly influenced by the ambient temperature to which the composite material is applied, and this paper describes detailed information for the best composite materials and their condition characteristic mechanical control by the electric heating.

521 TiNiファイバ強化知的複合材料の通電加熱によるファイバの収縮力を利用した制振効果(OS 先端材料の力学特性と計測技術(1))

521 TiNiファイバ強化知的複合材料の通電加熱によるファイバの収縮力を利用した制振効果(OS 先端材料の力学特性と計測技術(1))