METASTABLE STRUCTURE OF AUSTENITIC MANGANESE ALLOY AND PROSPECTS FOR CREATION OF PARTS BASED ON IT

Comparative microstructural studies and mechanical tests of an experimental austenic manganese alloy and typical structural materials have been carried out. As a result of the research, relative data have been revealed, indicating high mechanical properties of the experimental alloy, which makes it possible to recommend it for machine parts operating at high load-speed operating conditions and temperature exposure up to 700 0C.

Muscle hypertrophy and strength gains after resistance training with different volume matched loads: a systematic review and meta-analysis.

The purpose of this paper was to conduct a systematic review and meta-analysis of studies that compared muscle hypertrophy and strength gains between resistance training protocols employing very low (VLL<30% of 1RM or >35 RM), low (LL30%-59% of 1RM, or 16–35 RM), moderate (ML60%-79% of 1RM, or 8 -15RM) and high load (HL≥80% of 1RM, or ≤7 RM) with matched volume loads (sets x reps x weight). A pooled analysis of the standardized mean difference for 1RM strength outcomes across the studies showed a benefit favoring HL vs. LL and vs. ML; and favoring ML vs. LL. Results from LL and VLL indicated little difference. A pooled analysis of the standardized mean difference for hypertrophy outcomes across all studies showed no differences between the training loads. Our findings indicate that, when volume load is equated between conditions, the highest loads induce superior dynamic strength gains. Alternatively, hypertrophic adaptations are similar irrespective of the magnitude of load. NOVELTY BULLETS: • Training with higher loads elicits greater gains in 1RM muscle strength when compared to lower loads, even when volume load is equated between conditions. • Muscle hypertrophy is similar irrespective of the magnitude of load, even when volume load is equated between conditions.

When Less Is More: Investigating Factors Influencing the Distraction Effect of Virtual Reality From Pain

Virtual reality (VR) is a powerful method of redirecting attention away from pain. Yet, little is known about which factors modulate the size of this distraction effect. The aim of this study was to investigate the role of cognitive load and inter-individual differences in the cognitive and affective domain on heat pain thresholds during a VR game. Ninety healthy participants (mean age ± SD: 23.46 ± 3.28; 50% identified as male and 50% as female) played a low and high load version of a VR game while heat pain thresholds and heart rate were recorded. The effects of cognitive load were assessed by computing the difference in pain thresholds between the high and low load condition for each participant. In addition, we computed the difference in heart rate variability (HRV) measures between both conditions to explore whether these would be correlated with the difference in heat pain thresholds. Prior to the VR session, participants completed questionnaires about their emotional distress, pain-related cognitions, and different executive functioning tasks. Contrary to our expectations, not all participants benefitted from a higher load in terms of distraction from pain. Logistic regression analysis revealed that participants who reported more emotional distress were more likely to exhibit higher pain thresholds in the low relative to the high load condition. Accordingly, these participants tended to show marginally higher HRV in the low compared to the high load condition. Our study demonstrates that the potential benefits of an increased cognitive load in VR on pain sensitivity depends on individual differences in affective state.

Development of a Combined Bulging-Piercing Technique to Reduce Forming Load for a Long Semi-Hollow Stepped Part

This paper aims to develop a new forming technique to manufacture a long semi-hollow stepped part. Traditionally, hot backward extrusion is used. This technique is not suitable, because it requires a very high forming load acting on the die and punch especially at the contact between punch and workpiece. As a result, the service life of the punch is very low. Therefore, a new technique to overcome this problem is needed. A combined bulging-piercing technique was proposed and developed in this research. The main concept of this technique is to bulge the part by upsetting the workpiece between the punch and the counter-punch to generate high frictional contact pressure which will help to restrain the material sliding down to the die cavity during the piercing step. In other words, this technique utilizes frictional force at the die-workpiece interface to reduce the forming load of the punch. Finite element modeling was employed to investigate and determine the suitable level of the bulging which can reduce the forming load without generating any significantly high force to the counter-punch. Only experiments with the minimum forming load were selected and implemented to validate this concept, because other conditions with high load will risk to damage the punch and the machine press of the product line. The results show that this technique can reduce the forming load by almost 40%, and also control a good concentricity of the part and reduce the wall thickness variation.

Balancing earliness and tardiness within workload control order release: an assessment by simulation

Most Workload Control literature assumes that delivery performance is determined by tardiness related performance measures only. While this may be true for companies that directly deliver to end-customers, for make-to-stock companies or firms that are part of supply chains, producing early often means large inventories in the finished goods warehouse or penalties incurred by companies downstream in the supply chain. Some earlier Workload Control studies used a so-called time limit, which constrains the set of jobs that can be considered for order release, to reduce earliness. However, recent literature largely abandoned the time limit since it negatively impacts tardiness performance. This study revisits the time limit, assessing the use of different adaptive policies that restrict its use to periods of either low or high load. By using a simulation model of a pure job shop, the study shows that an adaptive policy allows to balance the contradictory objectives of delaying the release of orders to reduce earliness and to release orders early to respond to periods of high load as quick as possible. Meanwhile, only using a time limit in periods of high load was found to be the best policy.