Sheet molding compound characterization using spiral flow

Sheet molding compound (SMC) is a fiber‐reinforced polymeric composite. It is often used in automotive, marine, and industrial applications over other materials because of its high strength to density ratio, resistance to corrosion, and low cost. There is a demand in the SMC industry to be able to characterize SMC processability. This is particularly true for heavy truck body panels, one of the fastest growing applications of SMC. Because of their large size and high strength requirement, the molding forces have a major influence in the molding cycle. Also because of the long flow paths involved, the ability of the paste to carry glass needs to be properly characterized when developing new SMC materials. In this article, we demonstrate the benefits of using spiral flow as a processability tester. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rotational Restraint of Pile Caps during Lateral Loading

A pure fixed-head (zero-rotation) condition at the top of a group of laterally loaded piles is seldom achievable in the field, even when piles are installed in a group that is “rigidly” constrained by a stiff concrete pile cap. Assuming complete fixity during design (zero rotation at the pile head) can result in underestimated values of pile-head deflection, and incorrect estimates of the magnitude and the location of maximum bending moments. A simple and practical approach is presented for estimating the moment restraint that is provided by the pile cap at the top of a pile group. The moment restraint, represented by the rotational restraint coefficient (KMθ), serves as a boundary condition for analyzing groups of laterally loaded piles. Full-scale field tests performed on two pile groups with concrete pile caps show that the proposed method for estimating rotational restraint provides results that are in good agreement with measured field performance.     

Microstructural effects on the tensile properties and deformation behavior of a Ti-48Al gamma titanium aluminide

The effects of microstructure on the tensile properties and deformation behavior of a binary Ti-48Al gamma titanium aluminide were studied. Tensile-mechanical properties of samples with microstructures ranging from near γ to duplex to fine grained, near- and fully-lamellar were determined at a range of temperatures, and the deformation structures in these characterized by transmission electron microscopy (TEM). Microstructure was observed to exert a strong influence on the tensile properties, with the grain size and lamellar volume fraction playing connected, but complex, roles. Acoustic emission response monitored during the tensile test revealed spikes whose amplitude and frequency increased with an increase in the volume fraction of lamellar grains in the microstructure. Analysis of failed samples suggested that microcracking was the main factor responsible for the spikes, with twinning providing a minor contribution in the near-lamellar materials. The most important factor that controls ductility of these alloys is grain size. The ductility, yield stress, and work-hardening rate of the binary Ti-48Al alloy exhibit maximum values between 0.50 and 0.60 volume fraction of the lamellar constituent. The high work-hardening rate, which is associated with the low mobility of dislocations, is the likely cause of low ductility of these alloys. In the near-γ and duplex structures, slip by motion of 1/2<110] unit dislocations and twinning are the prevalent deformation modes at room temperature (RT), whereas twinning is more common in the near- and fully-lamellar structures. The occurrence of twinning is largely dictated by the Schmid factor. The 1/2<110] unit dislocations are prevalent even for grain orientations for which the Schmid factor is higher for <101] superdislocations, though the latter are observed in favorably oriented grains. The activity of both of these systems is responsible for the higher ductility at ambient temperatures compared with Al-rich single-phase γ alloys. A higher twin density is observed in lamellar grains, but their propagation depends on the orientation and geometry of the individual γ lamellae. The increase in ductility at high temperatures correlates with increased activity of 1/2<110] dislocations (including their climb motion) and twin thickening. The role of microstructural variables on strength, ductility, and fracture are discussed. This article is based on a presentation made in the symposium entitled “Fundamentals of Structural Intermetallics,” presented at the 2002 TMS Annual Meeting, February 21–27, 2002, in Seattle, Washington, under the auspices of the ASM and TMS Joint Committee on Mechanical Behavior of Materials.     

Rapid degradation of the mycotoxin patulin in man quantified by stable isotope dilution assays

The absorption and degradation of the mycotoxin patulin in man was quantified by using a recently developed stable isotope dilution assay. Application of this currently most sensitive method revealed a patulin content less than 200 ng l -1 in the blood serum of five consumers of apple juice. Likewise, no patulin was found in the serum of a volunteer, whose blood was drawn shortly after consumption of a juice containing a maximum tolerable amount of patulin. In further in vitro experiments, the degradation of patulin by reacting it with whole blood was investigated. After addition of 100 μg patulin to 9 ml blood, only 6.1% of the mycotoxin was detected after 2 min. It was concluded, therefore, that even high naturally occurring concentrations of patulin in foods are quickly degraded before reaching other tissues than the gastrointestinal tract.     

Effect of Floodwater Extraction on Mountain Stream Morphology

Floodwater is often extracted for consumptive purposes from western mountain streams in the United States. The long-term extraction of floodwater may alter the morphological and ecological balance of such streams. Scale model experiments based on eight mountain gravel-bed streams in Idaho were conducted to test the effects of floodwater extraction on stream morphology. The model channel transported a poorly sorted mix of model “gravel,” as well as copious amounts of model “sand.” The channel had a discontinuous floodplain, developed its own bar morphology, and contained large model colluvium as well as a bedrock platform. A mobile-bed equilibrium was first developed using a repeated hydrograph. The experiment was then repeated using a sliding cutoff discharge. The discharges in the hydrograph that were below a given cutoff discharge were reduced to 30% of bankfull discharge. By raising the cutoff discharge, it was possible to study the effect of increasing severity of floodwater extraction on stream morphology. The experiments indicated an increase in sand content on the bed surface and a decrease in the standard deviation of fluctuations in bed elevation with increasing severity of floodwater extraction.     

The Relational-Interdependent Self-Construal, Self-Concept Consistency, and Well-Being.

Examination of the assumptions underlying consistency perspectives in social and personality psychology reveals that they are based on an independent, individualistic view of the self. If the self is constructed as relational or interdependent with others, consistency may be less important in social behavior and well-being. Using a variety of measures of well-being, the studies showed that there is a weaker relation between consistency and well-being for individuals with a highly relational self-construal than for those with a low relational self-construal. Study 3 examined the association between the self-construal, consistency, authenticity, and well-being. These findings reveal the importance of a cultural analysis of theories of the self, personality, and well-being for further theory development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructured and Electro-Assisted High-Temperature Wettability of MgO in Contact with a Silicate Slag-Based on Fayalite

In this work, MgO samples have been microstructured by laser treatment and surfaces with a controlled stripe design have been manufactured. Sessile drop wetting measurements were performed in a special heating microscope by determining horizontal contact angles as well as contact angles as a function of surface inclination angles. In a further step, voltage was applied to ground MgO surfaces and the wetting behavior was registered as a function of the voltage level. Activation energy analysis was conducted for all the experiments.     

Computer aided kinetic modeling with KMT and KME

The complexity of many chemical and refining reaction systems and the thus-derived tedious and time-consuming process of building the associated kinetic models have been major obstacles in the use of fundamental kinetics in the solution of chemical engineering problems. This review summarizes work aimed at removing theses obstacles. Our recent work that has led to the enhancement of the Kinetic Modeler's Toolbox (KMT) and the development of the Kinetic Model Editor (KME) presents an end-to-end solution to the kinetic modeling process, including automated feedstock modeling, reaction network construction, kinetic rate estimation, model programming, process system configurations, model customizations, compilations, model execution and results analysis.