Experimental and Statistical Investigation of Machinability of AISI D2 Steel Using Electroerosion Machining Method in Different Machining Parameters

This study investigated the effects of machining parameters on the experimental and statistical results using the electric discharge method in the machining of AISI D2 cold work tool steel. The design of the experiment was established using the Taguchi L-18 method. The effect of the experiment parameters on the performance characteristics was analyzed by analysis of variance (ANOVA). As a result of the study, it was determined that increasing amperage and pulse time affected the surface roughness and hole diameter on the surface of the material. The lowest values for surface roughness, machining time, hole diameter, and crater diameter were determined as 2.085 mu m, 47 minutes, 12.010 mm, and 81.007 mu m, respectively. The highest wear amount was obtained as 0.604 grams with the processed parameters in the ninth experiment. When the signal-to-noise ratios were examined, the optimum combinations of the control factors for surface roughness, hole diameter, crater diameter, wear amount, wear rate, and processing time were determined as A(1)B(1)C(3), A(1)B(1)C(3), A(1)B(1)C(3), A(1)B(3)C(1), A(2)B(1)C(1), and A(1)B(3)C(3), respectively. According to the ANOVA results, the most important parameters affecting the test results for surface roughness, hole diameter, crater diameter, wear amount, material wear loss, and processing time were determined as amperage (49.34%), time-on (59.38%), amperage (55.65%), time-on (56.92%), amperage (51.42%), and amperage (78.02%), respectively. When the gray relational degree was calculated for the maximum and minimum values, the ideal factors for all output results were found to be the parameters applied in the third experiment.WOS:0007157831000012-s2.0-8511854209

Prevalence of femoroacetabular impingement and effect of training frequency on aetiology in paediatric football players

Purpose: The aim of this study was to determine the prevalence of asymptomatic radiographic findings of femoroacetabular impingement (FAI) in paediatric football players in different age groups and to investigate aetiological factors. Methods: Paediatric male athletes between 10 and 17 years of age from 8 soccer teams were recruited. In addition to an annual control check-up, anteroposterior pelvis and frog-leg radiographs as well as the curriculum vitae of the athletes, their injuries, and real-time complaints were recorded. The alpha angle, lateral centre-edge angle, Tonnis angle, and collodiaphyseal angle were measured and morphological abnormalities were noted. Results: There were 214 male football players with a mean age of 13.4 +/- 3.2 years included in the study. In the morphological analysis of hips, there was FAI in 30% of the athletes. In the analysis of FAI prevalence in 3 subgroups based on age (Group 1: 10-12 years [n = 25], Group 2: 13-15 years [n = 104], Group 3: 16-17 years [n = 85]), there was 0% FAI in Group 1, 19.1% in Group 2 and 60% in Group 3. In the analysis of aetiological factors, there was no significant difference between the right and left hips of players regarding alpha angles and FAI prevalence. However, the prevalence of FAI was higher in players who had been playing football for 3 years or more and who had been training for 12.5 hours/week or more. Conclusion: Training for 12.5 hours or more per week in paediatric football players doubled the risk development of FAI morphology

Persistent abdominal pain after exercise: An unexpected diagnosis

A 33-year-old male patient presented with pain in the abdominal muscles for 2 weeks. His complaint appeared after beginning strengthening exercises of the trunk muscles, and gradually increased in severity. He had no history of trauma to the abdominal region, comorbidities, complaints related to the gastrointestinal system, or drug use. A physical examination found nothing significant, except for tendernessin the left hypogastric area during palpatio

Effects of special exercise programs on functional movement screen scores and injury prevention in preprofessional young football players

To increase movement capacity and to reduce injury risk in young soccer players by implementing a special functional exercise program based on functional movement screen (FMS) and correctives. 67 young male athletes 14-19 years of age from a Super League Football Club Academy participated in the study. Functional movement patterns were evaluated with FMS assessment protocol. Deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability push-up, and rotatory stability were examined in FMS. Considering the FMS scores the number of intervention and control groups were defined as 24 and 43, respectively. Intervention program was composed of 1 hr twice a week sessions in total of 12 weeks with 4 weeks of mobility, 4 weeks of stability, and 4 weeks of integration exercises. At the end of 12-week intervention and control groups were re-evaluated with FMS protocol. Contact and noncontact sports injuries recorded during one season. In intervention group there was statistically significant difference in increase in total FMS scores (P<0.01), deep squat (P= 0.001), hurdle step (P<0.05), inline lunge (P<0.01), and trunk stability push-up (P<0.01). In control group total FMS, deep squat, and trunk stability push-up scores increased with a statistical difference (P<0.01, P<0.05, P= 0.01, respectively). The incidence of noncontact injury in control group was higher than intervention group (P<0.05). Periodic movement screening and proper corrections with functional training is valuable in order to create better movement capacity to build better physical performance and more effective injury prevention