Humidity effects on the fatigue of fiber reinforced polymers in micro/nano functional systems
Micro and nano functional systems like MEMS and smart systems are exposed to complex and very challenging service conditions (e.g., within airframe structures or in automotive applications under the hood or within battery cells). Therefore, long-term reliability and structural integrity of the chassis and the printed wiring boards is of rising concern. These parts are often made of fiber reinforced polymers (FRP). Recently, a new methodology for accelerated fatigue testing of FRP has been presented. It allows predictions of the structural fatigue lifetime of FRP for arbitrary temperatures and loading ratios based on three simple tests: visco-elastic DMA, constant strain rate tests, and high cycle fatigue tests at a limited number of temperatures and strain rates. However, this methodology considers dry samples only, which does not suffice for describing the behavior of micro/nano systems as mentioned before. The paper reports the approach to the expansion of this testing methodology to the effects of humidity. Choosing PCB material as typical example for FRP in micro/nano systems, the time / temperature shift functions have been determined for wet and dry samples. Subsequently, constant strain rate and high cycle fatigue tests have been performed. They show a substantial loss in strength and fatigue lifetime for FRP structures that were exposed humid environment. Determining the quantities measuring this reduction in structural reliability paves the way to the expansion of the fatigue testing methodology towards accounting for the humidity effect as well.
Prediction of tensile fatigue life under temperature environment for unidirectional CFRP
A method for prediction of fatigue strength under temperature environment was proposed for polymer composites and its validity was confirmed for the flexural fatigue strength of satin-woven CFRP laminates and others. This method is based upon the four hypotheses: (A) same failure process under constant strain-rate (CSR), creep, and fatigue loadings, (B) same time-temperature superposition principle for all failure strengths, (C) linear cumulative damage law for a nondecreasing stress process, and (D) linear dependence of fatigue strength upon stress ratio. Data are provided for tensile CSR, creep, and fatigue tests at various loading rates, frequencies, and temperatures in the longitudinal direction of unidirectional CFRP. In this paper, experimental verification of the prediction method is discussed for the tensile fatigue strength of unidirectional CFRP.
Nurse responsiveness to cancer patient expressions of emotion.
OBJECTIVE
This theoretically based study examined nurse responses to cancer patient expressions of emotion using a videotaped, simulated cancer patient.


METHODS
This study used an experimental crossover design with a videotaped patient expressing anger, sadness, and neutral emotion to elicit nurse responses. Seventy-four nurses from eight sites participated. Responses were coded using Roter interaction analysis system. Correlations explored relationships between variables that impact communication (age, gender, work experience, trait anxiety, work stress, self-efficacy). Regression models explored the effect of variables on nurse affective responsiveness.


RESULTS
Patient expressions of sadness elicited more affective responses than anger. Expressions of anger or neutral emotion elicited more instrumental behaviors than sadness. Variables such as age, work stress and work experience were significantly correlated. No variables predicted affective responsiveness to patient expressions of anger or sadness.


CONCLUSION
Nurse communication showed significant variation in response to patient emotional expressions. Understanding the relationships between demographic, personality, and work variables, and identification of new variables that influence nurse-patient communication, has implications for interventional studies.


PRACTICE IMPLICATIONS
Over 90% of the participants indicated that the videotape simulation would be a useful method for teaching and practicing communication skills with patients expressing emotions.