scholarly journals Conservar Património, a consolidation process

2021 ◽  
pp. 8-9
Author(s):  
Elin Figueiredo ◽  
Tiago Miguel Ferreira ◽  
Ana Zélia Miller ◽  
Sílvia O. Sequeira ◽  
Ana Claro
Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1951
Author(s):  
Yi Di Boon ◽  
Sunil Chandrakant Joshi ◽  
Somen Kumar Bhudolia

Fiber reinforced thermoplastic composites are gaining popularity in many industries due to their short consolidation cycles, among other advantages over thermoset-based composites. Computer aided manufacturing processes, such as filament winding and automated fiber placement, have been used conventionally for thermoset-based composites. The automated processes can be adapted to include in situ consolidation for the fabrication of thermoplastic-based composites. In this paper, a detailed literature review on the factors affecting the in situ consolidation process is presented. The models used to study the various aspects of the in situ consolidation process are discussed. The processing parameters that gave good consolidation results in past studies are compiled and highlighted. The parameters can be used as reference points for future studies to further improve the automated manufacturing processes.


2004 ◽  
Vol 53 (1) ◽  
Author(s):  
Carsten Hefeker ◽  
Friedrich Heinemann ◽  
Klaus F. Zimmermann

AbstractIn his contribution Carsten Hefeker points out that most of the official arguments concerning the necessity of the Stability and Growth Pact are not convincing. Nevertheless, a mechanism that credibly avoids excessive debts and deficits is needed in most member states. It would be more useful, however, if such rules would focus on overall debt rather than on deficits. In addition, he advocates to create an external control for such fiscal rules, independent from the Commission and ECOFIN. He concludes that the Pact does not need to become more flexible, but more credible.Friedrich Heinemann states that much of the recent reform debate on the Stability Pact is based on a fundamental misconception: The Pact has not been established as a guiding tool for welfare - maximising politicians, but in order to limit detrimental incentives from fiscal short-sightedness. “Stupid” elements like the three-per-cent deficit ceiling have a clear and beneficial strategic function as boundary within the national budgetary process. Furthermore, simple rules are superior to smart ones in increasing the political costs of high deficits in terms of public awareness. The critique on the pact′s missing flexibility is correct mainly regarding its lose logical link to long-run sustainability. Increasing flexibility in a cyclical sense, however, is not a reform priority. Already today the Pact leaves sufficient leeway for responsible politicians. Instead, the reform focus must be on depoliticising the pact in the sense of limiting Council power in the deficit procedure. More flexibility must not come without depoliticising. He recommends that any reform should only be carried into effect with a significant time lag in order to limit the reputation damage which would be the consequence of any quick institutional response to the Pact′s recent crisis.In his paper Klaus F. Zimmermann argues that the Stability and Growth Pact (SGP) has been subject to criticism ever since its inception. He points out that it overlooks business cycle developments within the framework of the consolidation process; it adopts a too short-term view of the stabilisation target which is also hardly under control of policy-makers; and it deals with policy imperfections in a sub-optimal way. Therefore, a reform of the SGP is urgent. The author suggests that the rules must be handled more flexibly. In his opinion, a mediumterm budgetary target and a focus on public expenditures to tackle the pro-cyclical bias is needed. To restore credibility, the task of supervision should be transferred to an independent European institution.


2007 ◽  
Vol 539-543 ◽  
pp. 2651-2656 ◽  
Author(s):  
C.J. Huang ◽  
E. Ghassemieh

A 3-D coupled temperature-displacement finite element analysis is performed to study an ultrasonic consolidation process. Results show that ultrasonic wave is effective in causing deformation in aluminum foils. Ultrasonic vibration leads to an oscillating stress field. The oscillation of stress in substrate lags behind the ultrasonic vibration by about 0.1 cycle of ultrasonic wave. The upper foil, which is in contact with the substrate, has the most severe deformation. The substrate undergoes little deformation. Apparent material softening by ultrasonic wave, which is of great concern for decades, is successfully simulated. The higher the friction coefficient, the more obvious the apparent material softening effect.


2014 ◽  
Vol 31 (2) ◽  
pp. 275-293 ◽  
Author(s):  
Duo Qin

Much of modern econometrics stems directly from the post-1940 works of Haavelmo and the Cowles Commission (CC) Monograph 10. This paper examines the consolidation process of the Haavelmo-CC research program mainly during the 1950–70 period from three aspects: (i) developments of econometrics textbooks, (ii) emerging themes and trends in econometric research, and (iii) the contribution of the program to empirical modeling of real-world issues. The examination reveals that the program has gained dominance primarily through its adherence to the scientific banner and style rather than its empirical relevance. The adoption of the hard science methodology is decisive in winning over the academic community; the taxonomy of econometrics into steps involving primarily specification, identification, and estimation has played a pivotal role in generating compartmentalized research topics with manageable technical challenge and also in facilitating the educational need for compiling self-contained subjects and definitely soluble questions.


2021 ◽  
Author(s):  
SIDDHESH S. KULKARNI ◽  
KAMRAN A. KHAN ◽  
REHAN UMER

Reinforcement compaction sometimes referred as consolidation process and is one of the key steps in various composite manufacturing processes such as autoclave and out-of-autoclave processing. The prepregs consist of semi-cured thermoset resin system impregnating the fibers. hence, the prepreg shows strong viscoelastic compaction response, which strongly depends on compaction speed and stress relaxation. modeling of time-dependent response is of utmost importance to understand the behavior of prepregs during different stages of composites manufacturing processes. The quasilinear viscoelastic (QLV) theory has been extensively used for the modeling of viscoelastic response of soft tissues in biomedical applications. In QLV approach, the stress relaxation can be expressed in terms of the nonlinear elastic function and the reduced relaxation function. The constitutive equation can be represented by a convolution integral of the nonlinear strain history, and reduced relaxation function. This study adopted a quasilinear viscoelastic modeling approach to describe the time dependent behavior of uncured-prepregs under compression. The model was modified to account for the compaction behavior of the prepreg under a compressive load. The deformation behavior of the prepreg is usually characterized by the fiber volume fraction, V . In this study, the material used was a 2/2 Twill weave glass prepreg (M26T) supplied by Hexcel® Industries USA. We performed a compaction experiment of the uncured prepreg at room temperature at different displacement rate and subsequent relaxation to describe the viscoelastic behavior of the prepreg. The model parameter calibration was performed using the trust-region-reflective algorithm in matlab to a selected number of test data. The calibrated model was then used to predict the rate dependent compaction and relaxation response of prepregs for different fiber volume fractions and strain rates.


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