Search results for " Strength"

Development of Composites with a Self-Healing Function

2015

This research aimed to realize experimentally the facilevascular self-healing system in epoxy glass fibre reinforced composite. Using flexiblepolytetrafluoroethylene tubes as removable preforms, the channels were embeddedinto both neat epoxy resin and unidirectional glass-fibre reinforced epoxy laminate.Room temperature curable epoxy resin with a surfactant and an amine-basedhardener were the components of the binary healing agent. The specimens oftapered double cantilever beam geometry were subjected to Mode I fracture tests.Fracture of specimens released the healing agent from channels and triggeredself-healing process of the crack. Tested neat epoxy resin specimensdemonstrated recovery o…

Associations between muscle strength, spirometric pulmonary function and mobility in healthy older adults

2014

Background: Pathological obstruction in lungs leads to severe decreases in muscle strength and mobility in patients suffering from chronic obstructive pulmonary disease. The purpose of this study was to investigate the interdependency between muscle strength, spirometric pulmonary functions and mobility outcomes in healthy older men and women, where skeletal muscle and pulmonary function decline without interference of overt disease. Methods: 135 69 to 81‐yr‐old participants were recruited into the cross‐sectional study, which was performed as a part of European study MyoAge. Full, partial and no mediation models were constructed to assess the interdependency between muscle strength (handgr…

Targeted exercise against osteoporosis: A systematic review and meta-analysis for optimising bone strength throughout life

2010

Background. Exercise is widely recommended to reduce osteoporosis, falls and related fragility fractures, but its effect on whole bone strength has remained inconclusive. The primary purpose of this systematic review and meta-analysis was to evaluate the effects of long-term supervised exercise (≥6 months) on estimates of lower-extremity bone strength from childhood to older age. Methods. We searched four databases (PubMed, Sport Discus, Physical Education Index, and Embase) up to October 2009 and included 10 randomised controlled trials (RCTs) that assessed the effects of exercise training on whole bone strength. We analysed the results by age groups (childhood, adolescence, and young and …

Neuromuscular function and bone geometry and strength in aging

2010

Exercise loading and bone structure

2009

The objective of this dissertation was to determine the types of exercise loading that are associated with the strength of bones. Four cross-sectional studies were conducted between 2004 and 2008 including 378 athletes and their 62 referents. Sixteen different sports were classified into five specific categories for the lower extremities and three categories for the upper extremities according to the type of exercise loading.Besides planar DXA-derived hip structural analysis, pQCT, and MRI methods allowing the assessment of true bone cross-sections were used for the bone structure analyses of the tibia, proximal femur, radius, and humerus. At the lower extremity, the high-impact exercise lo…

Flexural behaviour of calcarenite masonry walls reinforced with FRP sheets

2015

The use of fiber-reinforced polymers (FRP) for structural strengthening has become increasingly popular in recent years. Several applications of FRP have been proposed and applied, depending on the target of the technique, kind and/or material of the structural member. In particular, because of their great tensile strength, FRP materials are commonly used to enhance the out-of-plane behaviour of masonry walls, allowing to increase their strength, ductility and improving safety against overturning. For these reasons, FRP laminates are often applied in vulnerable ancient buildings in seismic areas to reinforce façades and walls with poor structural features. However, some issues arise when ad…

EFFECTIVENESS OF BASALT FIBRE-REINFORCED CEMENTITIOUS SYSTEMS IN CONFINING MASONRY MEMBERS: AN EXPERIMENTAL INVESTIGATION

2020

The use of composites based on fibre-reinforced polymers (FRPs) to strengthen masonry columns has become a common practice in the last decades. FRPs, however, exhibit some shortcomings when applied to masonry substrates, due to the organic nature of their matrix. For this reason, increasing attention is paid today to composites based on fibre-reinforced cementitious matrices (FRCMs), in which the polymeric matrix is replaced with an inorganic matrix (such as cementitious mortars). Cementitious matrices guarantee higher breathability and compatibility with the substrate, less sensitivity to debonding at the interfaces, and higher resistance to fire and high temperatures. Moreover, due to the…

Individuality of responses to bilateral and unilateral volume equated hypertrophic strength training in physically active men

2019

Purpose. The purpose of the present study was to investigate possible differences between unilateral and bilateral strength training during ten weeks progressive hypertrophic strength training and six weeks detraining period. Furthermore, it was examined possible different individual responders in muscle hypertrophy during strength training and, how those different responders would behave during the detraining phase following the training period. Methods. The present intervention included ten weeks of progressive hypertrophic resistance training followed by six weeks of detraining in healthy young men (n=24). Ultrasound was used to measure vastus lateralis (VL) muscle cross-sectional area (…

Isometric force-time parameters in monitoring of strength training : with special reference to acute responses to different loading resistances

2017

The aim of the present series of studies was to investigate acute neuromuscular responses to (1) different strength training loadings and using (2) different external resistances. In addition, chronic adaptations and dynamic performances were compared to (3) the changes in isometric force-time parameters at the group level, and to (4) the individual timing of the improvement in the rate of force development (RFD) due to hypertrophic or maximum strength followed by power strength training periods. The latter one was achieved by systematic, repeated monitoring. Sixty-nine physically active men (20-35 yrs), but not experienced in resistance training, took part in the present series of studies.…

Effect of Stacking Sequence and Sodium Bicarbonate Treatment on Quasi-Static and Dynamic Mechanical Properties of Flax/Jute Epoxy-Based Composites

2019

The present paper deals with the investigation of quasi-static and dynamic mechanical response of epoxy-based composites reinforced with flax and/or jute plain weave fabrics. In order to evaluate the influence of the stacking sequence, two monolithic laminates reinforced with flax or jute fibers and two hybrid flax/jute laminates were manufactured through the vacuum infusion technique. Furthermore, an eco-friendly and cost-effective surface treatment based on fiber soaking in a sodium bicarbonate solution was employed to improve the fiber-matrix adhesion. The mechanical characterization (by means of quasi-static flexural, dynamic mechanical thermal analysis and Charpy impact tests) allowed …