scholarly journals The effect of annealing on deformation and mechanical strength of tough PLA and its application in 3D printed prosthetic sockets

2021 ◽  
Vol 27 (11) ◽  
pp. 81-89
Author(s):  
Diede Christine Wijnbergen ◽  
Merel van der Stelt ◽  
Luc Martijn Verhamme
Keyword(s):  
Tensile Strength ◽  
Tensile Test ◽  
Material Properties ◽  
Poly Lactic Acid ◽  
Control Group ◽  
Iso Standard ◽  
Content Type ◽  
Prosthetic Socket ◽  
3D Printed ◽  
The Impact

Purpose Fused filament fabrication (FFF) using tough poly lactic acid (PLA) was determined to be the most suited method to achieve low-cost prosthetic sockets. However, improvement in the material properties is desirable to strengthen these sockets. This study aims to evaluate annealing as a potential method to improve material properties by a heat treatment of the object after 3D printing. Design/methodology/approach Four different annealing methods and a control group were tested according to ISO standard 527–1 and ISO standard 527–2. The four annealing methods included: oven; sand; water; and glycerol annealing. Tests were performed on longitudinal and transversal 3D printed samples. Deformation was determined on 3D printed test rings. Findings Annealing using an oven, sand and water resulted in a significant increase in tensile strength in longitudinally 3D printed tensile test samples. However, the tensile strength was decreased in the transversally 3D printed tensile test samples. The tensile modulus had no significant increase in the longitudinally and transversally printed samples. Sand annealing resulted in the least deformation, with a shrinkage of 2.04% of inner diameter and an increase in height of 1.99% for the horizontally annealed test rings. Research limitations/implications The annealing of prosthetic sockets is not recommended as a decrease in tensile strength in transversally printed tensile test samples was observed. More research is needed towards the strengthening of tough PLA in both print directions. Originality/value This paper fulfils the need for understanding the impact of annealing on 3D printed items intended for daily use, such as a prosthetic socket.

Open hole tensile testing of 3D printed parts using in-house fabricated PLA filament

2020 ◽  
Vol 26 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Harshit K. Dave ◽  
Ashish R. Prajapati ◽  
Shilpesh R. Rajpurohit ◽  
Naushil H. Patadiya ◽  
Harit K. Raval
Keyword(s):  
Tensile Strength ◽  
Layer Thickness ◽  
Process Parameters ◽  
Geometrical Shape ◽  
Content Type ◽  
Fused Deposition ◽  
Open Hole ◽  
Raster Angle ◽  
3D Printed ◽  
The Impact

Purpose Fused deposition modeling (FDM) is being increasingly used in automotive and aerospace industries because of its ability to produce specimens having difficult geometrical shape. However, owing to lack of critical information regarding the reliability and mechanical properties of FDM-printed parts at various designs, the use of 3D printed parts in these industries is limited. Therefore, the purpose of this paper is to investigate the impact of process parameters of FDM on the tensile strength of open-hole specimen printed using in-house-fabricated polylactic acid (PLA). Design/methodology/approach In the present study, three process parameters, namely, raster angle, layer thickness and raster width, are selected for investigation of tensile strength. To produce the tensile specimens in the FDM machine, the PLA filament is used which is fabricated from PLA granules using a single-screw extruder. Further, the experimental values are measured and critically analysed. Failure modes under tests are studied using scanning electron microscopy (SEM). Findings Results indicate that the raster angle has a significant effect on the tensile strength of open-hole tensile specimen. Specimens built with 0° raster angle, 200-µm layer thickness and 500-µm raster width obtained maximum tensile strength. Originality/value In this work, a new concept of testing a plate that has a rectangular shape and a circular hole at the centre is tested. Open-hole tensile test standard ASTM D5766 has been implemented for the first time for the FDM process.

Impact of processing parameters on tensile strength, in-process crystallinity and mesostructure in FDM-fabricated PLA specimens

2019 ◽  
Vol 25 (8) ◽  
pp. 1398-1410 ◽  
Author(s):  
Ognjan Luzanin ◽  
Dejan Movrin ◽  
Vassilis Stathopoulos ◽  
Pavlos Pandis ◽  
Tanja Radusin ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Layer Thickness ◽  
Process Model ◽  
Processing Parameters ◽  
Poly Lactic Acid ◽  
Extrusion Speed ◽  
Plate Temperature ◽  
Content Type ◽  
Designed Experiment ◽  
The Impact

Purpose This study aims to investigate the impact of layer thickness, extrusion temperature, extrusion speed and build plate temperature on the tensile strength, crystallinity achieved during fabrication (herein, in-process crystallinity) and mesostructure of Poly(lactic acid) specimens. Both tensile strength and in-process crystallinity were optimized and verified as the function of processing parameters, and their relationship was thoroughly examined. Design/methodology/approach The four key technological parameters were systematically varied as factors on three levels, using the statistically designed experiment. Surface response methodology was used to optimize tensile strength and crystallinity for the given ranges of input factors. Optimized factor settings were used in a set of confirmation runs, where the result of optimization was experimentally confirmed. Material characterization was performed using differential scanning calorimetry and X-ray diffraction analysis, while the effect of processing parameters on mesostructure was examined by scanning electron microscopy. Findings Layer thickness and its quadratic effect are dominant contributors to tensile strength. Significant interaction between layer thickness and extrusion speed implies that these parameters should always be varied simultaneously within designed experiment to obtain adequate process model. As regards, the in-process crystallinity, extrusion speed is part of two significant interactions with plate temperature and layer thickness, respectively. Quality of mesostructure is vital contributor to tensile strength during FDM process, while the in-process crystallinity exhibited no impact, remaining below the 20 per cent margin regardless of process parameter settings. Originality/value According to available literature, there have been no previously published investigations which studied the effect of process parameters on tensile strength, mesostructure and in-process crystallinity through systematic variation of four critical processing parameters.

Librarians, step out of the classroom!: how improved faculty-led IL instruction improves student learning

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Meagan Lacy ◽  
Alexandra Hamlett
Keyword(s):  
Student Learning ◽  
Research Process ◽  
Control Group ◽  
Student Survey ◽  
Content Type ◽  
Actual Application ◽  
Faculty Teaching ◽  
Survey Results ◽  
The Impact

PurposeIn most higher education institutions, information literacy (IL) instruction is usually considered the purview of librarians, not disciplinary faculty. However, a small but growing body of research indicates that students learn the research process best when these skills are taught in the context of a course or a discipline. For this reason, teaching faculty should share ownership of IL instruction — but how? In this case study, community college librarians explain how they successfully trained faculty to integrate IL into their English Composition courses and teach IL independently.Design/methodology/approachUsing a multimethods approach, the investigators draw on faculty interviews, student surveys, and content analysis of student essays to evaluate the impact of faculty-led IL instruction on student learning after one semester.FindingsFaculty reported that their instruction of IL was improved, and students work better as a result of their collaboration with the librarians. Compared to previous semesters, faculty perceived gains in terms of students’ ability to synthesize and cite evidence in their writing. Student survey results indicate perceived gains in their IL skills, but an assessment of their written work reveals a discrepancy between this perception and the actual application of these skills.Research limitations/implicationsBecause there is no control group, no conclusions can be drawn as to whether faculty-led IL instruction is as effective as librarian-led IL instruction or whether students’ academic performance improves due to faculty teaching IL. However, the purpose of this study is primarily descriptive. It addresses how other libraries may create a culture of shared ownership of IL instruction on their campuses.Practical implicationsThis study offers an alternative model to library instruction and suggests ways instruction librarians can prioritize their outreach and instructional efforts to maximize impact on student learning.Originality/valueWhile much has been written about how librarians can improve IL instruction, few studies mention the role of faculty. This case study starts the conversation.

Evaluating the effectiveness of interventions to reducing screen time in children: meta-analysis of randomized controlled trials

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Duygu Akçay ◽  
Nuray Barış
Keyword(s):  
Effect Size ◽  
Subgroup Analysis ◽  
Screen Time ◽  
Meta Analysis ◽  
Intervention Group ◽  
Evidence Base ◽  
Control Group ◽  
Content Type ◽  
Mean Differences ◽  
The Impact

Purpose The purpose of this paper is to evaluate the impact of interventions focused on reducing screen time in children. Design/methodology/approach Studies that aim to investigate the effects of interventions aimed at reducing the time spent in front of the screen (i.e. screen time). A Random-effects model was used to calculate the pooled standard mean differences. The outcome was to evaluate the screen time in children in the 0–18 age range. A subgroup analysis was performed to reveal the extent to which the overall effect size varied by subgroups (participant age, duration of intervention and follow). Findings For the outcome, the meta-analysis included 21 studies, and the standard difference in mean change in screen time in the intervention group compared with the control group was −0.16 (95% confidence interval [CI], −0.21 to −0.12) (p < 0.001). The effect size was found to be higher in long-term (=7 months) interventions and follow-ups (p < 0.05). Originality/value Subgroup analysis showed that a significant effect of screen time reduction was observed in studies in which the duration of intervention and follow-up was =7 months. As the evidence base grows, future researchers can contribute to these findings by conducting a more comprehensive analysis of effect modifiers and optimizing interventions to reduce screen time.

The effect of body-movement teaching, learning motivation and performance

2016 ◽  
Vol 24 (3) ◽  
pp. 414-437 ◽  
Author(s):  
Satoshi Sugahara ◽  
Hisayo Sugao ◽  
Steven Dellaportas ◽  
Takahiro Masaoka
Keyword(s):  
Body Movement ◽  
Learning Motivation ◽  
Control Group ◽  
Content Type ◽  
Entry Level ◽  
Quasi Experimental ◽  
And Performance ◽  
Teaching Learning ◽  
The Impact ◽  
Experimental Group

Purpose This research applies a quasi-experimental research method to investigate the impact of an innovative resource titled “Accounting Exercise” (teaching intervention using physical movement and lyrics) on learning motivation and performance on a group of students enrolled in a first-year undergraduate accounting course in Japan. Design/methodology/approach Five classes were randomly assigned to either an experimental group (two classes) or a control group (three classes). In the experimental group, 90 students participated in a 15-min “Accounting Exercise” at the commencement of lectures over three consecutive weeks. The remaining 133 students assigned to the control group did not participate in the Accounting Exercise. Findings The findings indicate that the Accounting Exercise provided stimuli in maintaining students’ learning motivation. This finding is important for entry-level students where learning motivation has the potential to influence students’ future decisions on major areas of study and career choices. Originality/value This finding is important for entry-level students where future career options are decided. This effect is also believed to contribute to reducing the declining numbers of students in accounting majors.

scholarly journals Determination of the Material Properties of the Reinforcement for Textile-Reinforced Concrete Elements

2021 ◽  
Author(s):  
Sergej Rempel ◽  
Marcus Ricker ◽  
Tânia Feiri
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Tensile Test ◽  
Material Properties ◽  
Construction Material ◽  
Gumbel Distribution ◽  
Mean Value ◽  
Elastic Behaviour ◽  
Textile Reinforced Concrete ◽  
Design Values

Abstract Textile-reinforced concrete has emerged in recent years as a new and valuable construction material. The design of textile-reinforced concrete requires knowledge on the mechanical properties of different textile types as well as their reinforcing behaviour under different loading conditions. Conventional load-bearing tests tend to be complex, time-consuming, costly and can even lack consistent specifications. To mitigate such drawbacks, a standardised tensile test for fibre strands was developed aiming at characterising the material properties needed for the design of a textile-reinforced concrete component. For the sake of this study, an epoxy resin-soaked AR-glass reinforcement was considered. The standardised tensile test uses a fibre strand with 160 mm length, which shall be cut out of a textile grid. The results show that the textile reinforcement has a linear-elastic behaviour, and the ultimate tensile strength can be statistically modelled by a Gumbel distribution. Furthermore, the results indicate that the modulus of elasticity is not influenced by the length or the number of fibre strands. Therefore, the mean value from the standardised test can be used for the design purpose. These findings are essential to derive an appropriate partial safety factor for the calculation of the design values of the tensile strength and can be used to determine the failure probability of textile-reinforced concrete components.

scholarly journals The Impact of Slicing Softwares on the Mechanical Properties of 3D Printed Parts

2020 ◽  
Vol 9 (2) ◽  
pp. 487-494
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
3D Printer ◽  
Stl File ◽  
3D Printed ◽  
Intersection Curves ◽  
The Impact

“Slicing tool” or “Slicing Software” computes the intersection curves of models and slicing planes. They improve the quality of the model being printed when given in the form of STL file. Upon analyzing a specimen that has been printed using two different slicing tools, there was a drastic variation on account of the mechanical properties of the specimen. The ultimate tensile strength and the surface roughness of the material vary from one tool to another. This paper reports an investigation and analysis of the variation in the ultimate tensile strength and the surface roughness of the specimen, given that the 3D printer and the model being printed is the same, with a variation of usage of slicing software. This analysis includes ReplicatorG, Flashprint as the two different slicing tools that are used for slicing of the model. The variation in the ultimate tensile strength and the surface roughness are measured and represented statistically through graphs. An appropriate decisive conclusion was drawn on the basis of the observations and analysis of the experiment on relevance to the behavior and mechanical properties of the specimen.

Help Me Grow Utah and the impact on family protective factors development

2018 ◽  
Vol 13 (1) ◽  
pp. 33-43
Author(s):  
Karen D. Hill ◽  
Brian J. Hill
Keyword(s):  
Child Development ◽  
Protective Factors ◽  
Protective Factor ◽  
Response Shift ◽  
Control Group ◽  
Content Type ◽  
Post Test ◽  
Response Shift Bias ◽  
And Control ◽  
The Impact

Purpose The purpose of this paper is to examine the development of family protective factors in participants of Help Me Grow Utah (HMGU), a community-based system that promotes child development, seeks early detection of developmental delays, and links families to services. Design/methodology/approach In this paper, standard quasi-experimental survey design was utilized. HMGU and control group participants completed the FRIENDS Protective Factors Survey, which was slightly modified into a retrospective pre-test and post-test format to address previous survey concerns of response-shift bias, self-serving assessments, and family maturation. Participants were asked to respond to ten questions at present and then again from the perspective of two years previous. Findings Participants in HMGU had statistically significant increases in protective factor scores in all but one subscale, with dramatic increases in two subscale questions on knowledge of parenting and child development. Control group scores statistically increased in four subscales, albeit at lower rates than HMGU participants. Interestingly, control group scores on two subscale questions relating to child maltreatment risk were significantly lower on post-tests as compared to their retrospective pre-test scores. Research limitations/implications Participants in HMGU clearly increased in the development of protective factors. Replication of this study is recommended and the need for a control group in protective factor studies is imperative. Practical implications Findings from this study suggest that child services focused on enhancing knowledge of parenting and child development might also expect to improve protective factors. One-on-one care coordination with families seems particularly effective. The findings might also benefit other social programs as they utilize retrospective pre-test, post-test, and control groups in their evaluations. Originality/value HMGU is the first affiliate to utilize retrospective pre-test/post-test methodology, which can overcome confounding results attributable to response-shift bias. Also, the use of a control group affords inclusion of natural maturation in considering findings.

The impact of individual differences on multitasking ability

2020 ◽  
Vol 69 (6) ◽  
pp. 1301-1319
Author(s):  
Derek E. Crews ◽  
Molly J. Russ
Keyword(s):  
Individual Differences ◽  
Personality Assessment ◽  
Employee Training ◽  
Control Group ◽  
Content Type ◽  
Initial Task ◽  
Gender And Age ◽  
Additional Task ◽  
Standards And Regulations ◽  
The Impact

PurposeThe study's purpose was to explore the impact of multitasking on efficiency and accuracy and the relationship between individual differences and multitasking ability.Design/methodology/approachAn experimental study was conducted with individuals that completed an in-box exercise and a personality assessment. Three groups were established as follows: those that completed the in-box exercise without interruption (control group), those that were given a portion of the same initial task but were then interrupted and given an additional task (low multitask group) and those that were given the same initial tasks, then interrupted three times (high multitask group).FindingsThe results show that there were significant effects of gender and age on multitasking efficiency. Females made fewer errors than males. Younger and older participants took more time to complete the experiment, which indicates an inverted U relationship and may mean that people become more effective at multitasking with experience and practice, but then less effective as they get older. The study also found that personality had no significant effect on multitasking efficiency.Research limitations/implicationsThe study was limited in that the sample was 91 percent female, did not include anyone over the age of 51 and did not measure intelligence or experience.Practical implicationsThe findings may have implications for employee training, evaluation and formulation of workplace standards and regulations.Orginality/valueThis study provides empirical research extending the understanding of the nature and impact of multitasking and individual differences based on gender, age and personality.

Evaluation of community-based psychological first aid in oncology

2019 ◽  
Vol 18 (4) ◽  
pp. 248-255
Author(s):  
Brandon L. Gray ◽  
Samuel Gaster ◽  
Christina Early ◽  
Amanda Reed
Keyword(s):  
Self Efficacy ◽  
Longitudinal Design ◽  
High Stress ◽  
First Aid ◽  
Care Staff ◽  
Control Group ◽  
Community Based ◽  
Content Type ◽  
Psychological First Aid ◽  
The Impact

Purpose Healthcare professionals work in high stress environments and may benefit from organizational efforts that enhance coping abilities. Community-based psychological first aid (CBPFA) is an evidence-informed program designed for building these skills and promoting resilience during stressful times. However, few studies have examined the effectiveness of CBPFA. The paper aims to discuss these issues. Design/methodology/approach This study examined the effectiveness of CBPFA training in promoting occupational self-efficacy and intentions to use CBPFA among oncology care staff over time using a longitudinal design. Findings Participants reported increased occupational self-efficacy and intentions to use CBPFA skills after completing training. These factors remained stable at one-month follow-up. Research limitations/implications The implications of these results are limited by the lack of a control group in the study’s design, relatively homogenous sample and participant dropout. Originality/value Despite the study’s limitations, these results represent an initial step in empirically examining the impact of CBPFA trainings and providing evidence that CBPFA may be an effective preparedness and development program in high-stress healthcare settings.

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