Hard Strips Research Articles

Evaluating fresh and hardened properties of mortar composite with different types of modified polyethylene terephthalate (PET) materials as additives: Modification effects, surface properties, shape factors

Plastic disposal has become a challenge due to its challenging degradability, and plastics recycling is one of the ideal methods. The utilization of recycled plastic in building materials has been widely researched as a possible way to store plastics permanently. An investigation on the modification and incorporation of polyethylene terephthalates (PET) on fresh and hardened properties of mortar composites (MCs) is performed in the study. The work provides understanding of the synergistic effects of plastic modification methods with different types of PET additives on MC properties and to explain behavior of modified PET in mortar composites. Modification methods include microwave radiation, chemicals oxidation and alkaline hydrolysis. These methods are applied on three types of structural PET materials (hard particles, hard strips and soft yarns). The properties of 0.5%–3% PET added MCs include workability, compressive strength (CS), flexural strength (FS) and toughness are determined. At 28 days, 3% hydrolysis-treated PET yarns significantly increased FS by 69.6% and improved toughness by almost 15 times while CS with 3% PET particles modified by microwave radiation and chemicals oxidation were comparable to the control.

Analysis of Mechanical Parameters in Multi-Pass Asymmetrical Rolling of Strip by Slab Method.

Mechanical parameters, time consumption and energy consumption are important considerations in the application of a certain rolling process. This study aims to investigate characteristics of the roll force, roll torque, roll power, rolling time and total work in multi-pass asymmetrical rolling of strip. Mathematic models were built using the slab method to calculate parameters in the asymmetrical rolling process, and the characteristics of these parameters were analyzed on the basis of simulation results. Mechanical parameters are affected by the change of deformation region type. When the speed ratio is less than the critical speed ratio, the roll force, absolute values of roll torque and roll power are found to increase with the increase in the speed ratio. After the speed ratio reaches the critical speed ratio, the roll force, roll torque and lower roll power keep constant, but the upper roll power continues increasing. The upper roll torque and upper roll power required by asymmetrical rolling are much greater than that by symmetrical rolling, which indicates that stronger drive shafts and more powerful drive motors are required by asymmetrical rolling. Compared with symmetrical rolling, asymmetrical rolling requires less roll force to obtain the same thickness reduction, especially for thin and hard strips. Rolling time can be saved at the cost of more energy consumption by using asymmetrical rolling with the same roll force to attain the same final thickness. The results and conclusions of this study can provide a reference for mill design and application of asymmetrical rolling in strip manufacturing.

Bistatic scattering at soft–hard strips and plates: method of moments (MoM), theory of edge diffraction (TED), and physical theory of diffraction (PTD) analysis

Diffraction at a strip with one face soft (electric) and the other hard (magnetic) is studied. New results obtained by the method of moments (MoM) are compared with the asymptotic theory of edge diffraction (TED) for the totally soft and hard strips. Attention is given to diffraction of oblique incident waves including the grazing diffraction. Novel analytic estimations for the forward and backward grazing scattering are established via the advanced physical theory of diffraction (PTD) free of grazing singularities. These estimations are demonstrated for the infinitely long strips and finite size rectangular plates.

Online electromagnetic monitoring of austenite transformation in hot strip rolling and its application to process optimization

Online detection and monitoring of phase transformation using non-destructive electromagnetic system in industrial hot strip mill processing of steels are reported. The system renders wide range of possibilities for advanced control and fine tuning of the hot rolling and run-out table cooling parameters. These in turn allow for process modifications to better control the microstructure of hot rolled bands. In particular, such modifications can attenuate the adverse effects of uncontrollable cooling of hot band coils that leads to severely non-homogeneous hot band microstructure. An example of application is given demonstrating how reducing the non-homogeneity of hot band microstructure with the aid of online hot strip mill electromagnetic system can help eliminating the off-thickness defects in advanced high strength steel full hard strips thus contributing to lowering the production costs and increasing the yield.

INVESTIGATION OF MODE SCATTERING BY HARD STRIPS IN LINED DUCTS USING COLLOCATION

When mounting acoustic liners inside the inlet duct of aircraft jet engines, hard strips exist in-between liner sections in order to hold them in place. It has been generally acknowledged, from experiments, that the existence of hard strips inside lined ducts affects the attenuation behaviour of the duct. The acoustic energy is scattered and rearranged among different modes so that it might be transferred into modes which are less attenuated by the liner. Moreover, cut-off modes may scatter into cut-on modes. In this paper, flow is included in the locally reacting liner case, which is more interesting to the aeronautics applications. Moreover, the duct is made finite and connected to two semi-infinite hard inlet and outlet ducts. By using mode matching, it is possible to input any mode at the inlet side and to study the modes on the outlet side. Comparisons are made between different hard strip cases and the splice-less liner case.

Rearing Dipha aphidivora, the pyralid predator of sugarcane woolly aphid Ceratovacuna lanigera, on its frozen host may be unfeasible

In Petri plate tests, neonate or third to fourth instar larvae of the predator Dipha aphidivora Meyrick (Lepidoptera: Pyralidae) were offered its host Ceratovacuna lanigera Zehntner (Homoptera: Aphididae), the woolly aphid of sugarcane, frozen and stored at −4°C, and thawed at room temperature before releasing the predator. In preliminary tests, neonate and grown-up larvae built webs, fed on aphids, pupated and emerged as adults. In two tests with neonate larvae, adult emergence was 45.5 and 80.0% in 17–21 days. The predator moths laid eggs on white coarse filter paper strips but not on hard paper strips of different colors placed in oviposition cages. Egg-laden filter paper or leaf bits placed in Petri plates with frozen aphids showed hatching but larvae did not survive long. Poor survival of neonate larvae in several additional tests with fresh or one-year old frozen aphid indicated that the method may not be useful for long-term rearing of the predator. Short-term survival of grown-up larvae on frozen aphid may enable the use of the latter as food for predator larvae in transit.

非円弧形ロール偏平に対応する調質圧延の弾塑性理論

This paper proposes a theory of cold rolling that considers roll deformation into a noncircular profile, for the analysis of temper rolling or the rolling of thin hard strips. Although models of this kind were presented by Matsumoto & Uehori in 1988, and more recently by other authors, the computation often fails when there is a large “neutral zone”, where plastic deformation is not proceeding because of roll flattening near the neutral point. In this paper, the elastic deformation of the strip being rolled is considered in order to ensure that the computation is accurate and stable even for a reduction ratio as small as 0.1%. The formulation of the strip is similar to Orowan’s rolling theory, but is modified with elastic deformation. The computing time is instantaneous. The computed rolling force and forward slip are compared with experimental results of wet temper rolling. It was found that there may be such a case as the backward-slip zone disappears and the entry elastic zone merges with the neutral zone into an integrated neutral zone when the exit tension is large compared with the entry tension.

New non-circular arc skin pass model

The presented skin pass model was developed for offline calculations in order to predict rolling forces and rolling torques very accurately over a wide range of applications including very thin and hard strips. The model takes into account radial (non-circular arc) as well as circumferential displacements of the work roll contour. This approach ensures an improved modelling of temper rolling, as the circumferential work roll displacements allow for the existence of slip as well as no slip zones inside the roll bite. The formation of a neutral zone instead of a neutral point is a consequence of this approach. The effect of circumferential displacements increases with decreasing strip thickness and draft in combination with higher friction (between work roll and strip) and cannot be neglected in such cases. The new model automatically detects the appearance of 'contained plastic flow'. Furthermore, the model offers the big advantage that the 'rollability' can be determined accurately, too. The simulation results were compared with finite element method (FEM) simulation results and were verified and calibrated against practical process data from an industrial skin pass mill. Excellent agreement between measured and predicted rolling forces and rolling torques was achieved. The developed model covers all specified requirements for a modern state of the art skin pass model. In the face of the trend to harder and thinner strips, the new skin pass model represents an applicable design tool to satisfy the most demanding customer requirements.

Hybrid analytical/numerical method for mode scattering in azimuthally non-uniform ducts

Sound-absorbing liners for ducts are often made in several azimuthal sections with acoustically hard strips, known as splices, between them. These can alter the liner's performance by causing scattering between mode orders, usually to the detriment of overall attenuation. Three-dimensional finite element methods, often involving specialised codes, have previously been used to predict the performance of such spliced liners. Here, an alternative approach is presented which uses a readily available two-dimensional finite element solver to find the modes of the spliced liner and then matches them to the analytical modes of the hard duct. The results are compared with three-dimensional finite element calculations to verify their accuracy. The method as described is for ducts with no flow, but can be extended to flow ducts if necessary.

Shape Controllability in New 6-High Mill (UC-4 Mill) with Small Diameter Work Rolls.

The work roll diameter of a new 6-high mill (UC-4 mill) is as small as that of cluster type mills. Shape control flexibility and the ability to roll flat strips in the UC-4 mill were examined experimentally and analytically, and it was found that the mill was suitable for thin strip rolling of stainless steel or other hard materials. The roll configuration of the UC-4 mill is asymmetrical in the longitudinal direction. Effects of this asymmetricity on shape control characteristics were also studied, and it was found that the shape controllability did not change with rolling direction. A cross buckle becomes a problem when thin and hard strips are rolled with small diameter work rolls. In the UC-4 mill, however, the occurrence of cross buckles did not increase despite of the smallness of the work roll diameter. Three actual plants are presently in production.

Diffraction of sound by hard strips and truncated wedges

Starting from rigorous diffraction solutions for single, hard, semi‐infinite wedges, it has long been possible to construct approximate solutions for more complex angular surfaces [A.D. Pierce, J. Acoust. Soc. Am. 55, 941–955 (1974)]. Demonstrated here is an exact procedure that formulates the multiple scatter between vertices of an angular body via the standard self‐consistent algorithm. This allows one to obtain the correct diffracted field of each vertex. Summing these together with the relevant incident and image fields leads to an exact solution for the full sound field. This is done here for the case of a plane harmonic incident sound field for (1) a truncated wedge and (2) a hard strip of width l. Numerical results for the latter model are shown to compare satisfactorily for all kl with experimental data [H. Medwin et al., J. Acoust. Soc. Am. 72, 1005–1013 (1982)]. This theoretical procedure yields, in the plane wave case, a formal estimate of the error incurred in the “double diffraction” approximation (i.e., the procedure that neglects all but the first two terms of the multiple scatter series). This error decreases like elkl/kl for increasing kl. It is then possible to confirm theoretically the observation of Medwin et al. who showed that, for the geometry of their strip experiment, this approximation is actually very good for kl≳ 3 and quite adequate in the region 1 < kl < 3, using the Biot‐Tolstoy rigorous impulsive point source solution for the perfect wedge [M. A. Biot and I. Tolstoy, J. Acoust. Soc. Am. 29, 381–391 (1957)] for their double‐diffraction solution. [Work supported by ONR.]