This paper presents the reliability estimation of fatigue strength of the material used for crank throw components. The material used for crank throw components is forged S34MnV steel and subsequently heat-treated by normalising and tempering. High cycle fatigue testing under fully reversed cycling (R = −1) was performed to determine the fatigue limit of the material. The staircase test method is used to obtain accurate values of the mean fatigue limit stress until a number of cycles up to 1E7 cycles. Subsequently, the fatigue test results depend strongly on the stress step and are evaluated by the Dixon-Mood formula. The values of mean fatigue strength and standard deviation predicted by the staircase method are 282 MPa and 10.6MPa, respectively. Finally, the reliability of the design fatigue strength in some selected probability of failure is calculated. Results indicate that the fatigue strength determined from accelerated staircase test is consistent with conventional fatigue testing. Furthermore, the proposed method can be applied for the determination of fatigue strength and standard deviation for design optimisation of S34MnV steel.
This study was aimed at examining the effects of different deoxidization methods on the physical properties of metallic melts by measuring the changes in the kinematic viscosity, electrical resistivity, surface tension, and density of the metallurgical melts during the heating and cooling processes. Our results indicate that high-temperature physical properties are consistently affected by specific elements and compounds.
The liquidus surface projection and isothermal section at 1,800°C in the Mo–Ti–C ternary system are examined using arc-melted alloys. A ternary transition peritectic reaction (L + Mo2C → Mo + TiC) takes place during solidification, which is apparently different from the ternary eutectic reaction (L → Mo + TiC + Mo2C) observed in a previous report. Since the composition of the eutectic reaction (L → Mo + TiC) shifts toward the Mo–Ti binary line with increasing Ti concentration, the volume fraction of the Mo phase and the interlamellar spacing of the Mo and TiC phases increase in the eutectic microstructure. At 1,800°C, the TiC phase in equilibrium with the Mo phase can contain more than 28 at% Mo and a Mo/TiC/Mo2C three-phase region exists at around Mo–15Ti–10C.
Remote operations of mobile machinery require reliable and flexible wireless communication. 5G networks will provide ultra-reliable and low latency wireless communications upon whichremote operations, real-time control and data acquisition can be implemented. In this paper we present a demonstration system and first experiments for remote mobile machinery control system utilizing 5G radio and a digital twin with a hardware-in-the-loop development system. Our experimental results indicate that with a suitable edge computing architecture an order of magnitude improvement in delay and jitter over exiting LTE infrastructure can be expected from future 5G networks.
The machinability information of Zr-based bulk metallic glasses (BMGs) are recently limited but essential to provide technological recommendation for the fabrication of the medical devices due to the material’s metastable nature. This study aims to investigate the material removal rate (MRR) and surface roughness under different current and pulse-on time of newly developed Ni- and Cu-free Zr-based BMG using sinking-electrical discharge machining (EDM). By using weightloss calculation, surface roughness test and scanning electron microscopy (SEM) observation on the workpiece after machining, both MRR and surface roughness were obtained to be increased up to 0.594 mm3/min and 5.50 μm, respectively, when the higher current was applied. On the other hand, the longer pulse-on time shifted the Ra into the higher value but lower the MRR value to only 0.183 mm3/min at 150 μs. Contrary, the surface hardness value was enhanced by both higher current and pulse-on time applied during machining indicating different level of structural change after high-temperature spark exposure on the BMG surface. These phenomena are strongly related to the surface evaporation which characterize the formation of crater and recast layer in various thicknesses and morphologies as well as the crystallization under the different discharge energy and exposure time.
The curing and cellular structure of natural rubber (NR)/silica composite foams were
investigated. The presence of an activator in the rubber formulation significantly
lowered the decomposition temperature of the azodicarbonamide foaming agent, which
allowed foaming before NR curing. Therefore, two foam methods were designed: foaming
initially at 90°C and then curing at 140°C, and foaming and curing
simultaneously at 140°C. Two-step foaming generated a lower cell density and
higher cell size. Incorporation of nano silica into NR increased the foam density,
but decreased the cell size. The higher foaming temperature restricted the bubble
growth because of a higher curing rate and inhibited cell coalescence.
Two-photon polymerization direct laser writing (TPP DLW) is an emerging technology
for producing advanced functional devices with complex three-dimensional (3D)
micro-structures. Tremendous efforts have been devoted to developing two-photon
polymerizable photo-sensitive nanocomposites with tailored properties. Light-induced
reconfigurable smart materials such as liquid crystalline elastomers (LCEs) are
promising materials. However, due to the difficulties in designing two-photon
polymerizable liquid crystal monomer (LCM) nanocomposite photoresists, it is
challenging to fabricate true 3D LCE micro-structures. In this paper, we report the
preparation of photo-sensitive LCE nanocomposites containing photothermal
nanomaterials, including multiwalled carbon nanotubes, graphene oxide and gold
nanorods (AuNRs), for TPP DLW. The printability of the LCE nanocomposites is assessed
by the fidelity of the micro-structures under different laser writing conditions. DLW
of GO/LCM photoresist has shown a vigorous bubble formation. This may be due to the
excessive heat generation upon rapid energy absorption of 780 nm laser energy.
Compared to pure LCM photoresists, AuNR/LCM photoresists have a lower laser intensity
threshold and higher critical laser scanning speed, due to the high absorption of
AuNRs at 780 nm, which enhanced the photo-sensitivity of the photoresist.
Therefore, a shorter printing time can be achieved for the AuNR/LCM photoresist.