Modeling of facesheet crack growth in titanium-graphite hybrid laminates, part I

Experimental observations have indicated that in titanium–graphite hybrid laminates, fatigue cracks in the titanium facesheets initiate at free edges as well as in areas of high stress concentration, such as holes and notches. In addition, a delaminated region between the facesheet and the intact plies develops and propagates in the wake of the facesheet crack. This paper investigates different modeling techniques for predicting the coupled damage growth. Two modeling approaches were applied; a two-dimensional bridged-crack (BC) model and the virtual crack closure technique (VCCT). The VCCT was applied in two and three-dimensional finite element models and the trends were shown to be the same for both cases. However, the trends predicted using the VCCT are significantly different than the BC model. The reasons for the discrepancies are discussed. The model predictions are compared to experimental results in the second part of this paper

A Phase 1 randomized, open-label clinical trial to evaluate the effect of a far-infrared emitting patch on local skin perfusion, microcirculation and oxygenation

Far-infrared radiation (FIR) has been investigated for reduction of pain and improvement of dermal blood flow. The FIRTECH patch is a medical device designed to re-emit FIR radiated by the body. This phase 1 study was conducted to evaluate the local effects of the FIRTECH patch on local skin perfusion, microcirculation and oxygenation. This prospective, randomized, open-label, parallel designed study admitted 20 healthy participants to a medical research facility for treatment for 31 h on three anatomical locations. During treatment, imaging assessments consisting of laser speckle contrast imaging, near-infrared spectroscopy, side-stream dark-field microscopy, multispectral imaging and thermography were conducted regularly on patch-treated skin and contralateral non-treated skin. The primary endpoint was baseline perfusion increase during treatment on the upper back. Secondary endpoints included change in baseline perfusion, oxygen consumption and temperature of treated versus untreated areas. The primary endpoint was not statistically significantly different between treated and non-treated areas. The secondary endpoints baseline perfusion on the forearm (least square means [LSMs] difference 2.63 PU, 95% CI: 0.97, 4.28), oxygen consumption (LSMs difference: 0.42 arbitrary units [AUs], 95% CI: 0.04, 0.81) and skin temperature (LSMs difference 0.35°C, 95% CI: 0.16, 0.6) were statistically significantly higher in treated areas. Adverse events observed during the study were mild and transient. The vascular response to the FIRTECH patch was short-lived suggesting a non-thermal vasodilatory effect of the patch. The FIRTECH patch was well tolerated, with mild and transient adverse events observed during the study. These results support the therapeutic potential of FIR in future investigations.Drug Delivery Technolog