Resin Flow During the Cure of Fiber Reinforced Composites

Experiments were performed studying resin flow during the cure of fiber reinforced, organic matrix composites using a system in which the resin was simulated by viscous liquids and the fibers either by layers of thin rods or by layers of porous plates. The flow pattern was observed and the flow rate was measured for different applied pressures. The data were compared to the results of the Springer-Loos model and excellent agreement was found bet ween the data and the model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67928/2/10.1177_002199838201600505.pd

Creep, Strength and Moisture Absorption of Adhesive Bonded FRP Joints

The effects of the environment on adhesive bonded single lap joints formed using XMC-3 and SMC-R50 composites were investigated. Tests were performed at temperatures of 23C and 93C with test coupons immersed in air, water, and 5% NaCl water mixture. The weight changes of both bonded joints (XMC-3 to SMC-R50 and SMC-R50 to SMC-R50) and unbonded materials were measured. Data were also ob tained showing the effects of moisture, temperature, and applied load on changes in weight, on creep deformation, lap shear strength, and separation modes of the joints.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68649/2/10.1177_073168448500400206.pd

Failure Time of Loaded Wooden Beams During Fire

A model is presented for predicting the failure time of loaded wooden beams of rectangular cross-section exposed to elevated temperatures or to fire. Failure times calculated by the model were compared to failure times measured in this study using 19.05 mm x 19.05 mm simply supported southern pine beams, and to failure times measured by the National Bureau of Standards during the fire of a full scale room. Reasonable agreements were found between the calculated failure times and the data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69007/2/10.1177_073490418300100407.pd

Model for Predicting Changes in the Strengths and Moduli of Timber Exposed To Elevated Temperatures

A model is presented for predicting changes in the tensile, compressive, and shear strengths and moduli of timber exposed to high temperature. The strengths and moduli of southern pine exposed for predetermined lengths of time to either 100, 160, 245, 400, 600 or 800 °C were measured. The accuracy of the model was assessed by comparing the strengths and the moduli predicted by the model to the data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68885/2/10.1177_073490418300100406.pd

Effects of Temperature and Moisture on Sheet Molding Compounds

A summary is given on the effects of moisture and temperature on the properties of chopped fiber reinforced sheet molding compounds. The properties surveyed include tensile strength and modulus, compression strength and modulus, shear strength and modulus, flexural strength and modulus, fatigue, creep, vibration damping, moisture absorption characteristics, and thermal expansion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68648/2/10.1177_073168448300200201.pd

Moisture Absorption of Graphite-Epoxy Composites Immersed in Liquids and in Humid Air

Moisture absorption of graphite-epoxy composites immersed in liquids and in himid air were investigated. The moisture content as a function of time and temperature was measured for three materials: Fiberite T300/1034, Hercules AS/3501-5 and Narmco T300/5208. Tests were per formed a) with the materials immersed in No. 2 diesel fuel, in jet A fuel, in aviation oil, in saturated salt water, and in distilled water (in the range of 300 to 322 K) and b)with the materials exposed to humid air (in the range 322 to 366 K). The results obtained were compared to available composite and neat resin data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68153/2/10.1177_002199837901300205.pd

Optical transmission losses in materials due to repeated impacts of liquid droplets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76812/1/AIAA-7018-720.pd

Parity-violating neutron spin rotation in hydrogen and deuterium

We calculate the (parity-violating) spin rotation angle of a polarized neutron beam through hydrogen and deuterium targets, using pionless effective field theory up to next-to-leading order. Our result is part of a program to obtain the five leading independent low-energy parameters that characterize hadronic parity-violation from few-body observables in one systematic and consistent framework. The two spin-rotation angles provide independent constraints on these parameters. Using naive dimensional analysis to estimate the typical size of the couplings, we expect the signal for standard target densities to be 10^-7 to 10^-6 rad/m for both hydrogen and deuterium targets. We find no indication that the nd observable is enhanced compared to the np one. All results are properly renormalized. An estimate of the numerical and systematic uncertainties of our calculations indicates excellent convergence. An appendix contains the relevant partial-wave projectors of the three-nucleon system.Comment: 44 pages, 17 figures; minor corrections; to be published in EPJ

Asymptotic behaviour of the gluon propagator from lattice QCD

We study the flavorless gluon propagator in the Landau gauge from high statistics lattice calculations. Hypercubic artifacts are efficiently eliminated by taking the $\sum p_\mu^4 \to 0$ limit. The propagator is fitted to the three-loops perturbative formula in an energy window ranging form $\sim$ 2.5 GeV up to $\sim$ 5.5 GeV. $\alpha_s$ is extracted from the best fit in a continuous set of renormalisation schemes. The fits are very good, with a $\chi^2$ per d.o.f smaller than 1. We propose a more stringent test of asymptotic scaling based on scheme independence of the resulting $\Lambda_{\bar MS}$. This method shows that asymptotic scaling at three loops is not reached by the gluon propagator although we use rather large energies. We are only able to obtain an effective flavorless three-loops estimate $\Lambda_{\bar MS}^{(3)}= 353 \pm 2 ^{+25}_{-10}$ MeV. We argue that the real asymptotic value for $\Lambda_{\bar MS}$ should plausibly be smaller.Comment: 16 pages, 9 figures, revTe

Mitigating risk of exceeding environmental limits requires ambitious food system interventions

Transforming the global food system is necessary to avoid exceeding planetary boundaries. A robust evidence base is crucial to assess the scale and combination of interventions required for a sustainable transformation. We developed a risk assessment framework, underpinned by a meta-regression of 60 global food system modeling studies, to quantify the potential of individual and combined interventions to mitigate the risk of exceeding the boundaries for land-system change, freshwater use, climate change, and biogeochemical flows by 2050. Limiting the risk of exceedance across four key planetary boundaries requires a high but plausible level of ambition in all demand-side (diet, population, waste) and most supply-side interventions. Attaining the required level of ambition for all interventions relies on embracing synergistic actions across the food system