Search results for "Strength"

Systematic Literature Reviews and Meta-Analyses

2009

SUMMARY Background: Because of the rising number of scientific publications, it is important to have a means of jointly summarizing and assessing different studies on a single topic. Systematic literature reviews, meta-analyses of published data, and meta-analyses of individual data (pooled reanalyses) are now being published with increasing frequency. We here describe the essential features of these methods and discuss their strengths and weaknesses. Methods: This article is based on a selective literature search. The different types of review and meta-analysis are described, the methods used in each are outlined so that they can be evaluated, and a checklist is given for the assessment of…

Effect of welding and heat treatment on the properties of UHSS used in automotive industry

2021

This paper deals with the undesired effects of the heat treatments on the mechanical properties of (UHSS) Ultra High Strength Steel used nowadays in automotive industry to improve crashworthiness performance of vehicles. The UHSS specimens were extracted from certain parts of the car body and subjected to different heat treatments. Four types of specimens were tested: untreated, welded with metal inert gas welding, heat treated at 800 °C, and heat treated at 1250 °C. All heat-treated specimens showed dramatically reduced values of strength. The results suggest that it is important to follow the official repair manuals avoiding unnecessary welding and improper heat treatments of UHSS. The ex…

The influence of calculation method and relative strength on the load-velocity relationship in bench press exercise

2021

Purpose The objective of this study was: (1) to compare the effect of the calculation method using average (Avalue), and best value (Bvalue) of Mean Propulsive Velocity (MPV) on the Load Velocity Profile (LVprofile) during the barbell bench press exercise in elite handball players. In addition, (2) to analyze the relationship between the individual coefficient of variation (CVind) of an incremental load protocol in the bench press exercise with relative strength (Frel) in professional handball players. Methods Nineteen elite international handball players (age 18 [±1] y; body mass 93 [±14] kg; height 191 [±6] cm) performed an incremental test during the barbell bench press exercise. General…

Effect of progressive collapse of central column on the push-down response of two-span beam-column substructures

2021

Abstract In this paper, a simplified model is proposed for hand calculation of the push-down curve of reinforced two-span beam-column substructures with the mid-span column subjected to a vertical load inducing progressive collapse response. The model takes into account the flexural, arch and catenary strength mechanisms and the axial stiffness of RC compressed columns. The model was validated against experimental data available in the literature. The expressions derived, in a closed form, were useful for hand calculation of push-down responses and robustness evaluation of RC framed structures. The derived explicit expressions can be applied in a step-by-step manner for tracing nonlinear be…

2020

Purpose: To examine the potential sex differences in adaptations to combined endurance and strength training in recreationally endurance trained (eumenorrheic) women (n = 9) and men (n = 10). Methods: Isometric (ISOMmax) and dynamic bilateral leg press (1RM), countermovement jump (CMJ), running performance (3,000 m time trial), lean mass and body fat % (LEAN and FAT% determined by dual X-ray absorptiometry) as well as serum testosterone and cortisol (TES and COR, respectively, measured using hormone-specific immunoassay kits) were examined before a control period and pre, mid, and post a supervised 10-week combined high-intensity interval endurance training (4 × 4 min intervals and 3 × 3 × …

Influence of Different Rehydration Protocols on Biomechanical Properties of Allogeneic Cortical Bone Plates: A Combined in-vitro/in-vivo Study

2020

Introduction: Allogeneic cortical bone plates (CP) are used for alveolar ridge augmentation. Since CP are freeze-dried and dehydrated during processing, the breaking strength (BS) and the flexibility (FX) are reduced, resulting in a relevant risk for plate fractures during insertion. The aim of this study was to evaluate the influence of rehydration time on the biomechanical properties (BS & FX) of CP in-vitro and in vivo.Material and Methods: 40 CP were randomly divided into four experimental groups. (A) untreated control (n = 10), rehydration for 10 (B), 30 (C) and 60 (D) minutes in 0.9% saline solution (n = 10 each). BS [Newton, N] and FX [mm] (force till fracture and distance of deflect…

Associations between changes in physical fitness and psychological difficulties status among Norwegian adolescents

2021

Abstract Objectives To investigate the associations for one-year changes in cardiorespiratory fitness, muscular strength and body mass index, with psychological difficulties status in adolescents. Methods Norwegian 14-15-year-olds (n = 925) participated in data collection at two time points separated by one year. Psychological difficulties were assessed via the Strengths and Difficulties questionnaire and data from follow-up serve as the dependent variable. Cardiorespiratory fitness (the Andersen-test), muscular strength (Eurofit) and body mass index were measured. Change scores were calculated from the physical fitness variables and serve as independent variables in linear mixed effects mo…

Dual phase titanium alloy hot forging process design: experiments and numerical modeling

2015

Titanium alloys are considered desirable materials when both good mechanical properties and weight reduction are required at the same time. This class of materials is widely used in those fields (aeronautics, aerospace) in which common steels and light-weight materials, e.g., aluminum alloys, are not able to satisfy all operative service conditions. During the last decade, forging of titanium alloys has attracted greater attention from both industrial and scientific/academic researchers because of their potential in providing a near net shaped part with minimal need for machining. In this paper, a numerical model of the forging sequences for a Ti-6Al-4V titanium alloy aerospace component is…

1986

Ultimate tensile properties and dart impact behaviour of coextruded films of LDPE and LLDPE were compared with those of films made from blends of the same resins. The effect of composition and of both blow up ratio and axial draw ratio of the blowing process on film properties was explored. The results indicate that, at least for semicompatible systems like that considered here, films made from blends and coextruded ones have mechanical properties very close to each other. Die Festigkeitseigenschaf ten und das Verhalten beim Kugelfalltest von coextrudiertcn Filmen aus LDPE und LLDPE wurden mit den entsprechenden Eigenschaften von aus Mischungen dieser Polymere hergestellten Filmen vergliche…

Reinforcement Efficiency of Cellulose Microfibers for the Tensile Stiffness and Strength of Rigid Low-Density Polyurethane Foams

2020

Rigid low-density closed-cell polyurethane (PU) foams are widely used in both thermal insulation and structural applications. The sustainability of PU foam production can be increased by using bio-based components and fillers that ensure both enhanced mechanical properties and higher renewable material content. Such bio-based foams were produced using polyols derived from rapeseed oil and microcrystalline cellulose (MCC) fibers as filler. The effect of MCC fiber loading of up to 10 wt % on the morphology, tensile stiffness, and strength of foams has been evaluated. For estimation of the mechanical reinforcement efficiency of foams, a model allowing for the partial alignment of filler fibers…