Trade, environment and development: implications for Caribbean countries

Includes bibliography

Big data and open data as sustainability tools: A working paper prepared by the Economic Commission for Latin America and the Caribbean

The two main forces affecting economic development are the ongoing technological revolution and the challenge of sustainability. Technological change is altering patterns of production, consumption and behaviour in societies; at the same time, it is becoming increasingly difficult to ensure the sustainability of these new patterns because of the constraints resulting from the negative externalities generated by economic growth and, in many cases, by technical progress itself. Reorienting innovation towards reducing or, if possible, reversing the effects of these externalities could create the conditions for synergies between the two processes. Views on the subject vary widely: while some maintain that these synergies can easily be created if growth follows an environmentally friendly model, summarized in the concept of green growth, others argue that production and consumption patterns are changing too slowly and that any technological fix will come too late. These considerations apply to hard technologies, essentially those used in production. The present document explores the opportunities being opened up by new ones, basically information and communication technologies, in terms of increasing the effectiveness (outcomes) and efficiency (relative costs) of soft technologies that can improve the way environmental issues are handled in business management and in public policy formulation and implementation.

Latin America and the Caribbean in the World Economy 2014: Regional integration and value chains in a challenging external environment

The 2014 edition of Latin America and the Caribbean in the World Economy: Regional integration and value chains amid challenging external conditions has four chapters. Chapter I examines the main features of the international context and their repercussions for world and regional trade. Chapter II looks at Latin American and Caribbean participation in global value chains and confirms that the region, with the exception of Mexico and Central America, has only limited linkages with the three major regional value chains of Asia, Europe and North America. This chapter also looks at how participation in value chains may contribute to more inclusive structural change, by analysing three core microeconomic aspects. Chapter III identifies various spheres in which regional integration and cooperation can help strengthen production integration between the economies of Latin America and the Caribbean. The fourth chapter explores the intra- and extraregional trade relations of the countries of the Caribbean Community (CARICOM) and considers how to strengthen production integration in the subregion by taking advantage of linkages beyond trade and building on commercial and production complementarities among the members. The chapter also reviews the differences between the countries in terms of income, population and production and export structure, in a context of marked macroeconomic vulnerability.

The employment situation in Latin America and the Caribbean: Labour productivity and distribution issues

Although the economies of Latin America and the Caribbean grew more slowly in 2011 than in 2010, there were some improvements on the employment front. Workers benefited from the region’s satisfactory economic performance in an increasingly complex international setting. The unemployment rate fell from 7.3% in 2010 to 6.7% in 2011 thanks to a halfpercentage- point gain in the urban employment rate. Both rates are at levels that have not been seen for a long time. The proportion of formal jobs with social benefits rose as well, and underemployment declined. The average wage and the minimum wage both increased in real terms, albeit only moderately. Economic performance and the employment situation varied widely among the subregions. The unemployment rate dropped by 0.6 percentage points in South America but 0.4 percentage points in the countries of the northern part of Latin America. In the countries of the Caribbean, the employment rate was up by 0.2 percentage points. The data show that substantial labour market gaps and serious labour-market insertion issues remain. This is especially the case for women and young people, for whom unemployment rates and other labour indicators are still unfavourable. The second part of this report looks at whether the fruits of economic growth and rising productivity have been distributed equitably between workers and companies. Between 2002 and 2008 (the most recent expansionary economic cycle), wages as a percentage of GDP fell in 13 of the 21 countries of the region for which data are available and rose in just 8. This points to redistribution that is unfavourable to workers, which is worrying in a region which already has the most unequal distribution of income in the world. Underlying this trend is the fact that, worldwide, wages have grown less than productivity. Beyond the ethical dimension of this issue, it jeopardizes the social and economic sustainability of growth. For example, one of the root causes of the recent financial crisis was that households in the United States responded to declining wage income by borrowing more to pay for consumption and housing. This turned out to be unsustainable in the long run. Over time, it undermines the labour market’s contribution to the efficient allocation of resources and its distributive function, too, with negative consequences for democratic governance. Among the triggers of this distributive worsening most often cited in the global debate are market deregulation and its impact on financial globalization, technological change that favours capital over labour, and the weakening of labour institutions. What is needed here is a public policy effort to help keep wage increases from lagging behind increases in productivity. Some countries of the region, especially in South America, saw promising developments during the second half of the 2000s in the form of a positive trend reversal in wages as a percentage of GDP. One example is Brazil, where a minimum wage policy tailored to the dynamics of the domestic market is considered to be one of the factors behind an upturn in the wage share of GDP. The region needs to grow more and better. Productivity must grow at a steady pace, to serve as the basis for sustained improvements in the well-being of the populace and to narrow the gap between the economies of Latin America and the Caribbean and the more advanced economies. And inequality must be decreased; this could be achieved by closing the productivity gap between upgraded companies and the many firms whose productivity is low. As set out in this report, the region made some progress between 2002 and 2010, with labour productivity rising at the rate of 1.5% a year. But this progress falls short of that seen in other regions such as Sub-Saharan Africa (2.1%) and, above all, East Asia (8.3%, not counting Japan and the Republic of Korea). Moreover, in many of the countries of the region these gains have not been distributed equitably. Therein lies a dual challenge that must be addressed: continue to increase productivity while enhancing the mechanisms for distributing gains in a way that will encourage investment and boost worker and household income. The Economic Commission for Latin America and the Caribbean (ECLAC) and the International Labour Organization (ILO) estimate that the pace of economic growth in the region will be slightly slower in 2012 than in 2011, in a global economic scenario marked by the cooling of several of the main economic engines and a high degree of uncertainty concerning, above all, prospects for the euro zone. The region is expected to continue to hold up well to this worsening scenario, thanks to policies that leveraged more favourable conditions in the past. This will be felt in the labour markets, as well, so expectations are that unemployment will edge down by as much as two tenths of a decimal point.

Population ageing in the Caribbean: An inventory of policies, programmes and future challenges

“We must be fully aware that while the developed countries became rich before they became old, the developing countries will become old before they become rich”. This statement made by Gro Harlem Brundtland, World Health Organization (WHO) Director-General, at the World Assembly on Ageing in 2002 in Madrid, reflects the challenges that the developing world is facing in the twentieth century. Population ageing is a global phenomenon, which is having and will have major implications on all aspects of human life in every society. This process is enduring and irreversible, as observed from differing patterns and distinct paces in various regions and countries all over the world. The United Nations has undertaken various efforts to repeatedly draw governments’ attention to the growing demand for answers to these encompassing and profound demographic changes. Various initiatives on the global as well as on the regional and subregional level have been undertaken to highlight the pressing need for concerted action. Of importance in this regard are the numerous agreements reached at the global conferences on social development, population and women orchestrated by the United Nations in the 1990s, which all refer to ageing as an issue of particular concern. The year 1999 was proclaimed by the General Assembly1 of the United Nations as the Year of Older Persons to recognize ageing as one of the major achievements but, at the same time, as one of the major challenges all populations have to cope with in the twentieth century. This continuous call for action culminated in the Second World Assembly on Ageing, which was held in Madrid 2002, where governments agreed to the implementation of a global action plan. This new Plan of Action focuses both on political priorities such as improvements in living conditions of older persons, combating poverty, social inclusion, individual self-fulfilment, human rights and gender equality. To an increasing degree attention is also devoted to such holistic and overarching themes as intergenerational solidarity, employment, social security, health and well-being. Mandated by the Second World Assembly on Ageing, the Population Division of the Economic Commission for Latin America and the Caribbean (ECLAC/CELADE) has convened the Regional Intergovernmental Conference on Ageing in November 2003 in Santiago, where a regional strategy for the implementation (ECLAC, 2003b) of the commitments reached in Madrid has been adopted. Further, a background document (ECLAC 2003a) on the situation of the elderly in the Latin American and Caribbean region, of which this document is a substantive part, has been presented to the meeting. Participating government officials formally committed themselves to work on a national follow-up strategy and to report on the progress made in the implementation of their commitments to the Ad hoc Committee on Population and Development to be convened in 2004.

Can the pattern of juvenile recruitment and population structure of the speckled swimming crab Arenaeus cribrarius (Decapoda: Brachyura) be determined by geographical variations?

This study evaluated the effect of environmental stimuli and selective pressures in different geographical areas along a latitudinal gradient, on the juvenile recruitment, population structure, and sex ratio of the speckled swimming crab Arenaeus cribrarius. Samples were collected monthly during 1 year in three locations along the Brazilian coast: Macaé, state of Rio de Janeiro (MAC, 22°47′ S, 41°45′ W); Ubatuba, São Paulo (UBA, 23°27′ S, 44°58′ W); and São Francisco do Sul, Santa Catarina (SFS, 26°08′ S, 48°34′ W). The specimens of A. cribrarius were identified, counted, sexed, and measured for maximum carapace width (CW). The largest juvenile found was in UBA (47.7 ± 1.36 mm); and the largest adult females and males in MAC (74.26 ± 0.93 and 77.04 ± 0.79 mm, respectively). Recruitment in MAC was continuous, whereas in UBA and SFS, recruitment showed seasonal characteristics. The sex ratio was skewed toward females only in UBA; in MAC and SFS, males and females were present in equal proportions. These results indicate that geographical variations can cause differences in the recruitment and population structure of A. cribrarius. These regional differences call attention to the necessity for improved management plans and control of shrimp fishing, which can affect population patterns such as juvenile recruitment, population structure and life history of the target species and species that are caught in bycatch from shrimping, such as the swimming crab A. cribrarius.

Environmental conservation and the Cerrado Biome: investigating knowledge and attitudes of Bauru residents

In today’s context of environmental degradation, environmental issues have increasingly become a focus of global discussion. Although many researchers emphasize the importance of knowledge and information in promoting environmental protection, research involving people’s notions about and attitudes toward the environment and establishing their connection with such knowledge is scarce. This lack of research led to the following inquiry: Is it possible to relate conservation actions and concern about a biome – in this case, the Cerrado – to the population’s level of knowledge about the environment in which they live? This research presents results from an investigation conducted in a representative population sample in Bauru, where there are fragments of a Cerrado Legal Reserve. The sampling approach used was probabilistic; it is based on random laws and can be submitted to statistical methods. The total sample (450 people) was divided into 90 people per Bauru region, 45 people female and 45 males. Each gender group was divided into three age groups: the first from 16 to 30 years, the second from 31 to 55 years and the third above 56 years. Through the questionnaire, we collected the following data from respondents: personal data such as salary, gender, age, level of education, notions/actions and intentions related to environmental conservation and general knowledge about the Cerrado. The result of the chi-square analysis is consistent with this finding, as it is less than 0.05, demonstrating a significant association between these two variables.

QUANTITATIVE TRAIT LOCI FOR AGRONOMIC AND END-USE QUALITY PERFORMANCE AND THE EFFECT OF SOILBORNE WHEAT MOSAIC VIRUS IN A HARD WINTER WHEAT POPULATION IN NEBRASKA

To better understand agronomic and end-use quality in wheat (Triticum aestivum L.) we developed a population containing 154 F6:8 recombinant inbred lines (RILs) from the cross TAM107-R7/Arlin. The parental lines and RILs were phenotyped at six environments in Nebraska and differed for resistance to Wheat soilborne mosaic virus (WSBMV), morphological, agronomic, and end-use quality traits. Additionally, a 2300 cM genome-wide linkage map was created for quantitative trait loci (QTL) analysis. Based on our results across multiple environments, the best RILs could be used for cultivar improvement. The population and marker data are publicly available for interested researchers for future research. The population was used to determine the effect of WSBMV on agronomic and end-use quality and for the mapping of a resistance locus. Results from two infected environments showed that all but two agronomic traits were significantly affected by the disease. Specifically, the disease reduced grain yield by 30% of susceptible RILs and they flowered 5 d later and were 11 cm shorter. End-use quality traits were not negatively affected but flour protein content was increased in susceptible RILs. The resistance locus SbmTmr1 mapped to 27.1 cM near marker wPt-5870 on chromosome 5DL using ELISA data. Finally, we investigated how WSBMV affected QTL detection in the population. QTLs were mapped at two WSBMV infected environments, four uninfected environments, and in the resistant and susceptible RIL subpopulations in the infected environments. Fifty-two significant (LOD≥3) QTLs were mapped in RILs at uninfected environments. Many of the QTLs were pleiotropic or closely linked at 6 chromosomal regions. Forty-seven QTLs were mapped in RILs at WSBMV infected environments. Comparisons between uninfected and infected environments identified 20 common QTLs and 21 environmentally specific QTLs. Finally, 24 QTLs were determined to be affected by WSBMV by comparing the subpopulations in QTL analyses within the same environment. The comparisons were statistically validated using marker by disease interactions. These results showed that QTLs can be affected by WSBMV and careful interpretation of QTL results is needed where biotic stresses are present. Finally, beneficial QTLs not affected by WSBMV or the environment are candidates for marker-assisted selection.

BENTHIC MACROFAUNA STRUCTURE IN THE NORTHEAST AREA OF TODOS OS SANTOS BAY, BAHIA STATE, BRAZIL: PATTERNS OF SPATIAL AND SEASONAL DISTRIBUTION

Structure of intertidal and subtidal benthic macrofauna in the northeastern region of Todos os Santos Bay (TSB), northeast Brazil, was investigated during a period of two years. Relationships with environmental parameters were studied through uni- and multivariate statistical analyses, and the main distributional patterns shown to be especially related to sediment type and content of organic fractions (Carbon, Nitrogen, Phosphorus), on both temporal and spatial scales. Polychaete annelids accounted for more than 70% of the total fauna and showed low densities, species richness and diversity, except for the area situated on the reef banks. These banks constitute a peculiar environment in relation to the rest of the region by having coarse sediments poor in organic matter and rich in biodetritic carbonates besides an abundant and diverse fauna. The intertidal region and the shallower area nearer to the oil refinery RLAM, with sediments composed mainly of fine sand, seem to constitute an unstable system with few highly dominant species, such as Armandia polyophthalma and Laeonereis acuta. In the other regions of TSB, where muddy bottoms predominated, densities and diversity were low, especially in the stations near the refinery. Here the lowest values of the biological indicators occurred together with the highest organic compound content. In addition, the nearest sites (stations 4 and 7) were sometimes azoic. The adjacent Caboto, considered as a control area at first, presented low density but intermediate values of species diversity, which indicates a less disturbed environment in relation to the pelitic infralittoral in front of the refinery. The results of the ordination analyses evidenced five homogeneous groups of stations (intertidal; reef banks; pelitic infralittoral; mixed sediments; Caboto) with different specific patterns, a fact which seems to be mainly related to granulometry and chemical sediment characteristics.

Reproductive migration and population dynamics of the blue crab Callinectes danae in an estuary in southeastern Brazil

Portunid crabs are an important resource in estuaries, and require appropriate management to guarantee their long-term availability. We investigated the population dynamics and reproduction of Callinectes danae in the Estuarine-Bay Complex of Sao Vicente, Sao Paulo, Brazil, to provide basic biological information for public policies for the management of this fishery. Monthly samples were obtained from March 2007 to February 2008 on eight transects, four in the estuary and four in the bay. A total of 2261 specimens (403 males, 1288 females, of which 570 were ovigerous) were collected. Males were significantly larger than females, and the size-frequency distribution was unimodal for males, females and ovigerous females. The sex ratio was nearly always skewed toward females (M:F - 1:4.6). C. danae showed seasonal-continuous reproduction, with high reproductive activity in the warmer season. C. danae breeds in the estuarine-bay complex, with males and juvenile females concentrated in the estuary. After copulation, fertilized females migrate to the estuary entrance and the bay, where ovigerous females are commonly found spawning in high-salinity areas. Therefore, to manage this important economic resource, both the estuary and the bay should be considered for protection, but special attention should be given to the estuary entrance during the summer months, when ovigerous females concentrate.

Consumer attitudes, knowledge, and behavior related to salt consumption in sentinel countries of the Americas

Objective. To describe individual attitudes, knowledge, and behavior regarding salt intake, its dietary sources, and current food-labeling practices related to salt and sodium in five sentinel countries of the Americas. Methods. A convenience sample of 1 992 adults (>= 18 years old) from Argentina, Canada, Chile, Costa Rica, and Ecuador (approximately 400 from each country) was obtained between September 2010 and February 2011. Data collection was conducted in shopping malls or major commercial areas using a questionnaire containing 33 questions. Descriptive estimates are presented for the total sample and stratified by country and sociodemographic characteristics of the studied population. Results. Almost 90% of participants associated excess intake of salt with the occurrence of adverse health conditions, more than 60% indicated they were trying to reduce their current intake of salt, and more than 30% believed reducing dietary salt to be of high importance. Only 26% of participants claimed to know the existence of a recommended maximum value of salt or sodium intake and 47% of them stated they knew the content of salt in food items. More than 80% of participants said that they would like food labeling to indicate high, medium, and low levels of salt or sodium and would like to see a clear warning label on packages of foods high in salt. Conclusions. Additional effort is required to increase consumers' knowledge about the existence of a maximum limit for intake and to improve their capacity to accurately monitor and reduce their personal salt consumption.

Characterization of Staphylococcus aureus isolates in milk and the milking environment from small-scale dairy farms of Sao Paulo, Brazil, using pulsed-field gel electrophoresis

This research aimed to evaluate the occurrence of Staphylococcus aureus isolates in milk and in the milking environment of 10 small-scale farms (<400 L/d) located in the regions of Franca and Ribeirao Preto, state of Sao Paulo, Brazil. Two-hundred twenty samples of milk were collected from individual cows, along with 120 samples from bulk tank milk, 389 samples from milking equipment and utensils (teat cups, buckets, and sieves), and 120 samples from milkers' hands. Fifty-six Staph. aureus strains were isolated from 849 analyzed samples (6.6%): 12 (5.5%) from milk samples of individual cows, 26 (21.7%) from samples of bulk tank milk, 14 (3.6%) from samples collected from equipment and utensils, and 4 (3.3%) from samples from milkers' hands. Pulsed-field gel electrophoresis typing of the 56 Staph. aureus isolates by SmaI restriction enzyme resulted in 31 profiles (pulsotypes) arranged in 12 major clusters. Results of this study indicate a low incidence, but wide distribution of Staph. aureus strains isolated from raw milk collected from individual cows and surfaces of milkers' hands and milking equipment in the small-scale dairy farms evaluated. However, the high percentage of bulk milk samples found with Staph. aureus is of public health concern because raw, unprocessed milk is regularly consumed by the Brazilian population.

The importance of mesofauna and decomposition environment on leaf decomposition in three forests in southeastern Brazil

We examined the effects of soil mesofauna and the litter decomposition environment (above and belowground) on leaf decomposition rates in three forest types in southeastern Brazil. To estimate decomposition experimentally, we used litterbags with a standard substrate in a full-factorial experimental design. We used model selection to compare three decomposition models and also to infer the importance of forest type, decomposition environment, mesofauna, and their interactions on the decomposition process. Rather than the frequently used simple and double-exponential models, the best model to describe our dataset was the exponential deceleration model, which assumed a single organic compartment with an exponential decrease of the decomposition rate. Decomposition was higher in the wet than in the seasonal forest, and the differences between forest types were stronger aboveground. Regarding litter decomposition environment, decomposition was predominantly higher below than aboveground, but the magnitude of this effect was higher in the seasonal than in wet forests. Mesofauna exclusion treatments had slower decomposition, except aboveground into the Semi-deciduous Forest, where the mesofauna presence did not affect decomposition. Furthermore, the effect of mesofauna was stronger in the wet forests and belowground. Overall, our results suggest that, in a regional scale, both decomposers activity and the positive effect of soil mesofauna in decomposition are constrained by abiotic factors, such as moisture conditions.

Added sugars: consumption and associated factors among adults and the elderly. São Paulo, Brazil

OBJECTIVE: To investigate added sugar intake, main dietary sources and factors associated with excessive intake of added sugar. METHODS: A population-based household survey was carried out in São Paulo, the largest city in Brazil. Cluster sampling was performed and the study sample comprised 689 adults and 622 elderly individuals. Dietary intake was estimated based on a 24-hour food recall. Usual nutrient intake was estimated by correcting for the within-person variance of intake using the Iowa State University (ISU) method. Linear regression analysis was conducted to identify factors associated with added sugar intake. RESULTS: Average of energy intake (EI) from added sugars was 9.1% (95% CI: 8.9%; 9.4%) among adults and 8.4% (95% CI: 8.2%; 8.7%) among the elderly (p < 0.05). Average added sugar intake (% EI) was higher among women than among men (p < 0.05). Soft drink was the main source of added sugar among adults, while table sugar was the main source of added sugar among the elderly. Added sugar intake increased with age among adults. Moreover, higher socioeconomic level was associated with added sugar intake in the same group. CONCLUSIONS: Added sugar intake is higher among younger adults of higher socioeconomic level. Soft drink and table sugar accounted for more than 50% of the sugar consumed.

Some issues concerning the dynamic response and damage of composite laminates subjected to low velocity impact

Abstract. This thesis presents a discussion on a few specific topics regarding the low velocity impact behaviour of laminated composites. These topics were chosen because of their significance as well as the relatively limited attention received so far by the scientific community. The first issue considered is the comparison between the effects induced by a low velocity impact and by a quasi-static indentation experimental test. An analysis of both test conditions is presented, based on the results of experiments carried out on carbon fibre laminates and on numerical computations by a finite element model. It is shown that both quasi-static and dynamic tests led to qualitatively similar failure patterns; three characteristic contact force thresholds, corresponding to the main steps of damage progression, were identified and found to be equal for impact and indentation. On the other hand, an equal energy absorption resulted in a larger delaminated area in quasi-static than in dynamic tests, while the maximum displacement of the impactor (or indentor) was higher in the case of impact, suggesting a probably more severe fibre damage than in indentation. Secondly, the effect of different specimen dimensions and boundary conditions on its impact response was examined. Experimental testing showed that the relationships of delaminated area with two significant impact parameters, the absorbed energy and the maximum contact force, did not depend on the in-plane dimensions and on the support condition of the coupons. The possibility of predicting, by means of a simplified numerical computation, the occurrence of delaminations during a specific impact event is also discussed. A study about the compressive behaviour of impact damaged laminates is also presented. Unlike most of the contributions available about this subject, the results of compression after impact tests on thin laminates are described in which the global specimen buckling was not prevented. Two different quasi-isotropic stacking sequences, as well as two specimen geometries, were considered. It is shown that in the case of rectangular coupons the lay-up can significantly affect the damage induced by impact. Different buckling shapes were observed in laminates with different stacking sequences, in agreement with the results of numerical analysis. In addition, the experiments showed that impact damage can alter the buckling mode of the laminates in certain situations, whereas it did not affect the compressive strength in every case, depending on the buckling shape. Some considerations about the significance of the test method employed are also proposed. Finally, a comprehensive study is presented regarding the influence of pre-existing in-plane loads on the impact response of laminates. Impact events in several conditions, including both tensile and compressive preloads, both uniaxial and biaxial, were analysed by means of numerical finite element simulations; the case of laminates impacted in postbuckling conditions was also considered. The study focused on how the effect of preload varies with the span-to-thickness ratio of the specimen, which was found to be a key parameter. It is shown that a tensile preload has the strongest effect on the peak stresses at low span-to-thickness ratios, leading to a reduction of the minimum impact energy required to initiate damage, whereas this effect tends to disappear as the span-to-thickness ratio increases. On the other hand, a compression preload exhibits the most detrimental effects at medium span-to-thickness ratios, at which the laminate compressive strength and the critical instability load are close to each other, while the influence of preload can be negligible for thin plates or even beneficial for very thick plates. The possibility to obtain a better explanation of the experimental results described in the literature, in view of the present findings, is highlighted. Throughout the thesis the capabilities and limitations of the finite element model, which was implemented in an in-house program, are discussed. The program did not include any damage model of the material. It is shown that, although this kind of analysis can yield accurate results as long as damage has little effect on the overall mechanical properties of a laminate, it can be helpful in explaining some phenomena and also in distinguishing between what can be modelled without taking into account the material degradation and what requires an appropriate simulation of damage. Sommario. Questa tesi presenta una discussione su alcune tematiche specifiche riguardanti il comportamento dei compositi laminati soggetti ad impatto a bassa velocità. Tali tematiche sono state scelte per la loro importanza, oltre che per l’attenzione relativamente limitata ricevuta finora dalla comunità scientifica. La prima delle problematiche considerate è il confronto fra gli effetti prodotti da una prova sperimentale di impatto a bassa velocità e da una prova di indentazione quasi statica. Viene presentata un’analisi di entrambe le condizioni di prova, basata sui risultati di esperimenti condotti su laminati in fibra di carbonio e su calcoli numerici svolti con un modello ad elementi finiti. È mostrato che sia le prove quasi statiche sia quelle dinamiche portano a un danneggiamento con caratteristiche qualitativamente simili; tre valori di soglia caratteristici della forza di contatto, corrispondenti alle fasi principali di progressione del danno, sono stati individuati e stimati uguali per impatto e indentazione. D’altro canto lo stesso assorbimento di energia ha portato ad un’area delaminata maggiore nelle prove statiche rispetto a quelle dinamiche, mentre il massimo spostamento dell’impattatore (o indentatore) è risultato maggiore nel caso dell’impatto, indicando la probabilità di un danneggiamento delle fibre più severo rispetto al caso dell’indentazione. In secondo luogo è stato esaminato l’effetto di diverse dimensioni del provino e diverse condizioni al contorno sulla sua risposta all’impatto. Le prove sperimentali hanno mostrato che le relazioni fra l’area delaminata e due parametri di impatto significativi, l’energia assorbita e la massima forza di contatto, non dipendono dalle dimensioni nel piano dei provini e dalle loro condizioni di supporto. Viene anche discussa la possibilità di prevedere, per mezzo di un calcolo numerico semplificato, il verificarsi di delaminazioni durante un determinato caso di impatto. È presentato anche uno studio sul comportamento a compressione di laminati danneggiati da impatto. Diversamente della maggior parte della letteratura disponibile su questo argomento, vengono qui descritti i risultati di prove di compressione dopo impatto su laminati sottili durante le quali l’instabilità elastica globale dei provini non è stata impedita. Sono state considerate due differenti sequenze di laminazione quasi isotrope, oltre a due geometrie per i provini. Viene mostrato come nel caso di provini rettangolari la sequenza di laminazione possa influenzare sensibilmente il danno prodotto dall’impatto. Due diversi tipi di deformate in condizioni di instabilità sono stati osservati per laminati con diversa laminazione, in accordo con i risultati dell’analisi numerica. Gli esperimenti hanno mostrato inoltre che in certe situazioni il danno da impatto può alterare la deformata che il laminato assume in seguito ad instabilità; d’altra parte tale danno non ha sempre influenzato la resistenza a compressione, a seconda della deformata. Vengono proposte anche alcune considerazioni sulla significatività del metodo di prova utilizzato. Infine viene presentato uno studio esaustivo riguardo all’influenza di carichi membranali preesistenti sulla risposta all’impatto dei laminati. Sono stati analizzati con simulazioni numeriche ad elementi finiti casi di impatto in diverse condizioni di precarico, sia di trazione sia di compressione, sia monoassiali sia biassiali; è stato preso in considerazione anche il caso di laminati impattati in condizioni di postbuckling. Lo studio si è concentrato in particolare sulla dipendenza degli effetti del precarico dal rapporto larghezza-spessore del provino, che si è rivelato un parametro fondamentale. Viene illustrato che un precarico di trazione ha l’effetto più marcato sulle massime tensioni per bassi rapporti larghezza-spessore, portando ad una riduzione della minima energia di impatto necessaria per innescare il danneggiamento, mentre questo effetto tende a scomparire all’aumentare di tale rapporto. Il precarico di compressione evidenzia invece gli effetti più deleteri a rapporti larghezza-spessore intermedi, ai quali la resistenza a compressione del laminato e il suo carico critico di instabilità sono paragonabili, mentre l’influenza del precarico può essere trascurabile per piastre sottili o addirittura benefica per piastre molto spesse. Viene evidenziata la possibilità di trovare una spiegazione più soddisfacente dei risultati sperimentali riportati in letteratura, alla luce del presente contributo. Nel corso della tesi vengono anche discussi le potenzialità ed i limiti del modello ad elementi finiti utilizzato, che è stato implementato in un programma scritto in proprio. Il programma non comprende alcuna modellazione del danneggiamento del materiale. Viene però spiegato come, nonostante questo tipo di analisi possa portare a risultati accurati soltanto finché il danno ha scarsi effetti sulle proprietà meccaniche d’insieme del laminato, esso possa essere utile per spiegare alcuni fenomeni, oltre che per distinguere fra ciò che si può riprodurre senza tenere conto del degrado del materiale e ciò che invece richiede una simulazione adeguata del danneggiamento.