Study the Electrical Properties of Surface Mount Device Integrated Silver Coated Vectran Yarn

Smart textiles have attracted huge attention due to their potential applications for ease of life. Recently, smart textiles have been produced by means of incorporation of electronic components onto/into conductive metallic yarns. The development, characterizations, and electro-mechanical testing of surface mounted electronic device (SMD) integrated E-yarns is still limited. There is a vulnerability to short circuits as non-filament conductive yarns have protruding fibers. It is important to determine the best construction method and study the factors that influence the textile properties of the base yarn. This paper investigated the effects of different external factors, namely, strain, solder pad size, temperature, abrasion, and washing on the electrical resistance of SMD integrated silver-coated Vectran (SCV) yarn. For this, a Vectran E-yarn was fabricated by integrating the SMD resistor into a SCV yarn by applying a vapor phase reflow soldering method. The results showed that the conductive gauge length, strain, overlap solder pad size, temperature, abrasion, and washing had a significant effect on the electrical resistance property of the SCV E-yarn. In addition, based on the experiment, the E-yarn made from SCV conductive thread and 68 Ω SMD resistor had the maximum electrical resistance and power of 72.16 Ω and 0.29 W per 0.31 m length. Therefore, the structure of this E-yarn is also expected to bring great benefits to manufacturing wearable conductive tracks and sensors.

The Development of a Gracilis and Quadriceps Tendons Calibration Device for Uniaxial Tensile Tests

To determine the biomechanical properties of the distal tendon of the gracilis muscle and the upper third of the quadriceps femoris muscle used for reconstruction of the medial patellofemoral ligament (MPFL), it is necessary to develop a calibration device for specimen preparation for uniaxial tensile tests. The need to develop this device also stems from the fact that there is currently no suitable regulatory or accurate protocol by which soft tissues such as tendons should be tested. In recent studies, various methods have been used to prepare test specimens, such as the use of different ratios of gauge lengths, different gripping techniques, etc., with the aim of obtaining measurable and comparable biomechanical tissue properties. Since tendons, as anisotropic materials, have viscoelastic properties, the guideline for manufacturing calibrator devices was the ISO 527-1:1993 standard, used for testing polymers, since they also have viscoelastic behaviour. The functionality of a calibrator device was investigated by preparing gracilis and quadriceps tendon samples. Fused deposition modeling (FDM) technology was used for the manufacturing of parts with complex geometry. The proposed calibrator could operate in two positions, horizontal and vertical. The maximum gauge length to be achieved was 60 mm, with the maximum tendon length of 120 mm. The average preparation time was 3 min per tendon. It was experimentally proven that it is possible to use a calibrator to prepare tendons for tensile tests. This research can help in the further development of soft tissue testing devices and also in the establishment of standards and exact protocols for their testing.

Study on the accelerated-point distribution of floating fibers in the drafting zone

The motion of floating fibers in the drafting zone has a significant effect on the sliver quality after drafting. In this study, the distribution of the accelerated point of floating fibers in the drafting area was simulated based on the distribution of fibers and frictional forces during the drafting process. The simulated results denoted that the acceleration distribution of the floating fibers was more concentrated and closer to the front roller as the drafting ratio increases. The distributions of accelerated points of the floating fibers became more and more decentralized and further away from the front roller as the gauge length grew when the other parameters remained constant. In the simulation, the frictional forces of the other floating fibers moving at high velocity and low velocity and the actual contact relationships of fibers in the drafting zone were taken into consideration. Moreover, whether the fiber lengths are identical or not, the simulated accelerated-point distributions of the floating fibers were demonstrated to conform more to the actual values compared to other models. Hence, the developed model can offer effective reference from the point of view of the distribution of accelerated points in order to realize the simulation of roller drafting.

Study on Test Methods of Tensile Properties of Continuous Alumina Fiber Bundles

In this paper, the effects of different sample clamping modes, curing time of the adhesive during sample preparation, gauge length of the sample and tensile rate on the tensile properties of continuous alumina fiber bundles are briefly introduced. These parameters can accurately affect the tensile properties of alumina fiber bundles.

Effective Young’s Modulus Estimation of Natural Fibers through Micromechanical Models: The Case of Henequen Fibers Reinforced-PP Composites

In this study, Young’s modulus of henequen fibers was estimated through micromechanical modeling of polypropylene (PP)-based composites, and further corroborated through a single filament tensile test after applying a correction method. PP and henequen strands, chopped to 1 mm length, were mixed in the presence of maleic anhydride grafted polypropylene (MAPP). A 4 wt.% of MAPP showed an effective enhancement of the interfacial adhesion. The composites were mold-injected into dog-bone specimens and tensile tested. The Young’s modulus of the composites increased steadily and linearly up to 50 wt.% of fiber content from 1.5 to 6.4 GPa, corresponding to a 327% increase. Certainly, henequen fibers showed a comparable stiffening capacity of PP composites than glass fibers. The intrinsic Young’s modulus of the fibers was predicted through well established models such as Hirsch or Tsai-Pagano, yielding average values of 30.5 and 34.6 GPa, respectively. The single filament test performed to henequen strands resulted in values between 16 and 27 GPa depending on the gauge length, although, after applying a correction method, a Young’s modulus of 33.3 GPa was obtained. Overall, the present work presents the great potential for henequen fibers as PP reinforcement. Moreover, relationships between micromechanics models and filament testing to estimate Young’s modulus of the fibers were explored.

The seismic wavefield as seen by Distributed Acoustic Sensing (DAS) arrays: local, regional and teleseismic sources

Distributed acoustic sensing (DAS) exploiting fibre optic cables provides a means for high-density sampling of the seismic wavefield. The scattered returns from multiple laser pulses provide local averages of strain rate over a finite gauge length, and the nature of the signal depends on the orientation of the cable with respect to the passing seismic waves. The properties of the wavefield in the slowness-frequency domain help to provide understanding of the nature of DAS recordings. For local events the dominant part of the strain rate can be extracted from the difference of ground velocity resolved along the fibre at the ends of the gauge interval, with an additional contribution just near the source. For more distant events the response at seismic frequencies can be represented as the acceleration along the fibre modulated by the horizontal slowness resolved in the same direction, which means there is a strong dependence on cable orientation. These representations of the wavefield provide insight into the character of the DAS wavefield in a range of situations from a local jump source, through a regional earthquake to teleseismic recording with different cable configurations and geographic locations. The slowness domain representation of the DAS signal allows analysis of the array response of cable configurations indicating the important role of the slowness weighting associated with the effect of gauge length. Unlike seismometer arrays the response is not described by a single generic stacking function. For high frequency waves, direct stacking enhances P, SV waves and Rayleigh waves; an azimuthal weighted stack provides retrieval of SH and Love waves at the cost of enhanced sidelobes in the array response.

Influence of Various Gauge Lengths, Root Spacing and Root Numbers on Root Tensile Properties of Herbaceous Plants

The mechanical properties of root system play an important role in soil reinforcement by plants. Root tensile properties are affected by many factors. It is necessary to explore the mechanical properties of root system and the influencing factors. In this study, tensile tests were conducted on roots of Kochia scoparia (L.) Schrad and Artemisia sacrorum Ledeb to study root tensile properties, including maximum tensile force, tensile strength and elastic modulus under the three factors, gauge length (50, 100, 150, and 200 mm), root spacing (0, 1, and 2 cm) and root number (single root, double roots, and triple roots). The results showed that the maximum tensile force, tensile strength, and elastic modulus of the roots decreased with increasing gauge length in power functions. Under 100 mm gauge length, the maximum tensile force, tensile strength and elastic modulus decreased with increasing root spacing, but the effect of root spacing considered in this study on the maximum tensile force and tensile strength was not significant. Besides, with increasing root number, the maximum tensile force increased, tensile strength, and elastic modulus decreased. These findings stretched our understanding of the relationship between gauge length, root spacing and root number on root tensile characteristics, and provided the necessary data basis for root tensile properties and soil reinforcement by plants.

Guided Waves Mode Filtering Using Fiber Bragg Grating Sensors

Guided waves (GW) allow fast inspection of a large area and hence have received great interest from the structural health monitoring (SHM) community. Fiber Bragg grating (FBG) sensors offer several advantages but their use for GW sensing has been limited due to their limited sensitivity. FBG sensors in the edge-filtering configuration have overcome this issue with sensitivity and there is a renewed interest in their use. It has been seen that depending on the ratio of the wavelength of the propagating wave to the gauge length of the FBG, the mechanism of the transduction of the wave measurement is different. A large ratio leads to a more uniform strain over the FBG leading to a shift in the frequency, while a non-uniform strain due to a short wavelength, leads to the peak widening. The present paper studies this phenomena and develops a signal processing technique for the filtering of the modes.