Analysis of delamination of composite laminates via extended finite element method based on the layerwise displacement theory and cohesive zone method

Composite laminates are being more employed as fundamental structures due to its low weight and high stiffness. To predict the material response in presence of damage can be demanding due to composite’s complex nature. Hence, superior computational models should be further investigated to speculate a more accurate composite behavior. This paper proposes an extended finite element procedure, based on the layerwise displacement theory, to simulate delamination to composite laminate. It is assumed a cohesive behavior to the damaged domain, described by a traction separation law. An extra degree of freedom associated to the strong discontinuity (delamination) is added at each layer top and bottom surface for out-of-plane displacement. This extra degree of freedom is only active on the failed nodes. To validate the model, a pre-delaminated composite analysis is performed and compared to results already reported in the literature. In addition, all stress components can be precisely calculated due to layer wise displacement field assumption, without any concern about the membrane and shear locking, not to mention its greater computational efficiency when compared to equivalent three-dimensional elements. Therefore, in the present work, it is shown the limitations and potentialities when a cohezive formulation is combined to extended finite element method using a new kind of approach. Additionally, this formulation makes easier to model delaminations using finite element method keeping a good accuracy without the need of cumbersome finite element models.

The touch-screen generation: Trends in Dutch parents’ perceptions of young children’s media use from 2012–2018

Based on a time-lag model, this study tested for changes in young children’s (1–6 years) home access and use of digital media in the 2012–2018 period as well as in their parents’ views on such media. What it found was that in only a few years the digital devices available to children have become more mobile (tablets and smartphones), more accessible, and more numerous in these children’s bedrooms, especially in single-parent households. Also, on average children have strongly increased their daily media use—up to 102 minutes. This is especially true for both younger children (3 years or less, plus 30 minutes) and children in middle to highly educated households (plus 25 minutes). Our findings support the complementary media adoption theory more than the displacement theory. Over the years parents have tended more and more to use digital media as ‘babysitters’, while they also found it increasingly difficult to stop their children from using such media, which may have major implications for parenting support activities.

An Experimental Investigation of Body Displacement Theory in Restrained Eaters

Body Displacement Theory posits that individuals with eating and weight concerns may mislabel feelings of ineffectiveness as feeling fat. Study 1used a non-clinical sample to create an Implicit Association Test for body image (IAT-BI) to measure implicit body dissatisfaction, as body displacement is thought to be an automatic cognitive/affective process. The IAT-BI was moderately and significantly correlated with explicit measures of body dissatisfaction, body shame, and restrained eating. In Study 2, an experimental manipulation was used to induce ineffectiveness in a non-clinical sample, and effects on implicit and explicit body image and related variables were measured. Contrary to hypotheses, feeling ineffective did not lead to feeling fat in comparison to those in a control condition. These findings may suggest that body displacement was not successfully induced by the manipulation, or that body displacement may be process unique to those with eating disorders. The implications of the study are discussed.

An Experimental Investigation of Body Displacement Theory in Restrained Eaters

Body Displacement Theory posits that individuals with eating and weight concerns may mislabel feelings of ineffectiveness as feeling fat. Study 1used a non-clinical sample to create an Implicit Association Test for body image (IAT-BI) to measure implicit body dissatisfaction, as body displacement is thought to be an automatic cognitive/affective process. The IAT-BI was moderately and significantly correlated with explicit measures of body dissatisfaction, body shame, and restrained eating. In Study 2, an experimental manipulation was used to induce ineffectiveness in a non-clinical sample, and effects on implicit and explicit body image and related variables were measured. Contrary to hypotheses, feeling ineffective did not lead to feeling fat in comparison to those in a control condition. These findings may suggest that body displacement was not successfully induced by the manipulation, or that body displacement may be process unique to those with eating disorders. The implications of the study are discussed.

Printed Versus Electronic Books: Uses and Preference of Mass Media Students in Lahore

This study is an exertion to determine the preference of university students regarding the usage of electronic books. Postulates of displacement theory were applied to find out the reasons behind students’ adoption of online mode of reading and its effects on learning outcome. The study has examined that if the printed books will be totally replaced by the electronic version or not. A sample of 150 university students studying in the Mass Communication department was selected. Survey methodology was employed to find answers to the research questions. The findings of the study revealed that students preferred using electronic books to printed books. The e-books are considered cost-friendly, easy to access and portable. With the help of findings, it was concluded that e-books had become part and parcel of the life of students, but at the same time, there would be a preference for reading printed books.

Consuming a difficult past unapproved: Chairman Mao as commodity

What role does consumption play in remembering a difficult past unacknowledged by the state? By analyzing the consumption of Chairman Mao symbols in contemporary China, this article explores the memory of a difficult past under censorship with ambiguous rules, that is, imposed discursive ambiguity, and puts forward a theory of mnemonic displacement centering on two generational mechanisms: denial and diversion. The “attendant generation” has experienced the past, reads the discursive ambiguity conservatively and consumes the Mao symbol as denial of the difficult past. The “posterior generation” has no autobiographical memory of the past, reads the discursive ambiguity more openly and consumes the Mao symbol as diversion of mnemonic themes. As a result, the difficult past is displaced and forgotten. This article contributes to memory studies not only by theorizing a type of difficult past under discursive ambiguity but also by developing a displacement theory of remembering and forgetting.

Design and Analysis of a Drilling Fixture

The Automation field is rapidly taking over the production and manufacturing sectors because of its heightened performance with improved accuracy and precision. Therefore, it is essential to understand the application and the significance of the involvement of automation in conventional drilling machines. The CAD geometry of the project is prepared in Solid Works, and finite element analysis considering the von misses stress, and displacement theory is carried out to find the effects of external loads on the motors and critical components of the fixture. The analysis where performed based on load calculated to be of 580.75 N, which gives stresses ranging of 1.466 to 117.7 MPa in the components. The project goal underscores the advantages of automation in drilling, including identifying and correcting errors occurring due to manual handling of systems. This project raises procedures for maintaining, setting up the work and work holding devices to get the job done accurately

The Race Between Deterrence and Displacement: Theory and Evidence from Bank Robberies

Security measures that deter crime may unwittingly displace it to neighboring areas, but evidence of displacement is scarce. We exploit precise information on the timing and locations of all Italian bank robberies and security guard hirings/firings over a decade to estimate deterrence and displacement effects of guards. A guard lowers the likelihood a bank is robbed by 35-40%. Over half of this reduction is displaced to nearby unguarded banks. Theory suggests optimal policy to mitigate this spillover is ambiguous. Our findings indicate restricting guards in sparse, rural markets and requiring guards in dense, urban markets could be socially beneficial.