The development of a new mandibular osteosynthesis plate: an application of the Ashby approach

Mandible fractures are among the most common bone injuries in facial traumas. Currently, mandibular fracture repair is carried out with an appropriate osteosynthesis plate. These osteosynthesis plates are also used to provide mastication function as soon as possible after operation. Therefore, the plates employed should ensure functional, mechanical, and morphological rehabilitation. Many researchers have reported that the titanium osteosynthesis plates currently used for mandibular defects are often subject to excessive stress. This excessive stress may lead to unexpected fractures of the plates. Unexpected fractures have been indicated as a mechanical weakness of titanium osteosynthesis plates. The aim of the present study is to investigate the mechanical stability and deformation behaviour of commercially available titanium mandibular osteosynthesis plates, as well as to design and develop a new osteosynthesis plate with better mechanical stability. In the first stage of this investigation, an analytical study was carried out to determine the optimum cross-sectional shape for the new plates. Subsequently, the cross-sectional shapes for the new plates were validated by numerical methods. Finally, the project was completed by manufacturing the plates and conducting static mechanical experiments of the developed plates. The mandibular osteosynthesis plates developed here are shown to exhibit improved mechanical stability.     

The intergenerational continuity of observed early parenting: A prospective, longitudinal study.

The authors report the results from a prospective, longitudinal study of cross-generational parenting quality in a lower socioeconomic status sample of moderate ethnic diversity (N = 61). The study extends previous research on intergenerational continuity of parenting in several significant ways: (a) Assessments in both generations were based on direct observation, (b) assessments were made at the same age (24 months) in both generations, (c) there were controls for later parenting in the first generation, and (d) there were controls for critical background factors (stress, socioeconomic status, child and parent IQ). An observed parenting-quality composite showed moderate stability (r = .43) across generations, and findings held after controlling for all other factors. A possible special role for early parenting experience and the extensive research needed to demonstrate it are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Friction stir welding of AISI 304 austenitic stainless steel

The objective of this work is to demonstrate the feasibility of friction stir welding (FSW) AISI 304 austenitic stainless steels. The tool used was formed of a tungsten‐based alloy. The specimens were welded on an 11 kW vertical milling machine. Defect‐free welds were produced on 2.5 mm plates of hot‐rolled AISI 304 austenitic stainless steels at travel speeds ranging from 40 to 100 mm/min with a constant rotating speed of 1000 rpm. Tensile strengths and hardness values of the weld interface were determined and microstructure features of these samples were investigated.     

Microstructures and mechanical properties of friction stir welded dissimilar copper/brass joints

In this study, an experimental investigation has been carried out on microstructure and mechanical properties of friction stir welded copper/brass dissimilar joints. Effect of axial tool force to welding quality has been investigated under obtained optimal tool rotation rate and tool traverse speed conditions. The tool for the dissimilar copper/brass friction stir welding manufactured from X155CrMoV12–1 cold work tool steel with material number of 1.2379. The friction stir welding quality was investigated by welding surface inspections, microstructural studies, micro hardness measurements and tensile tests. The experimental studies have shown that constant axial tool force during pre‐heating and during welding process are very important. As a result, by using 2.5–3 kN of axial tool force during pre‐heating and 5.5 kN of axial tool force during welding process, copper/brass dissimilar joints with well appearance and higher mechanical strength can be obtained.     

Effect of layer thickness and print orientation on strength of 3D printed and adhesively bonded single lap joints

Three-dimensional printing is the common name given to various techniques used to manufacture different objects. Fused deposition technique is a commonly used additive manufacturing technology in prototyping and production. Fused deposition modelling systems are limited in terms of shape and size of parts. Printing parts with less support material, for parts too large to print in a single operation or for parts with fine details, sectioning and adhesively bonding is the solution for manufacturing. According to adhesion theory, the strength of adhesively bonding between three-dimensional printed parts is affected by surface roughness. Effects of layer thickness and print orientation on adhesion strength of parts manufactured with three-dimensional printing were experimentally studied. As a result of the study, it was found that the edgewise orientation had the highest bonding strength in lower layer thicknesses, while flatwise orientation had the highest bonding strength in higher layer thicknesses.     

Effects of the printing parameters on short-term creep behaviors of three-dimensional printed polymers

Polylactic acid (PLA), despite its widespread use in three-dimensional (3D) printing technique, is lacking in the literature on creep behavior due to the printing parameters. Also, the potential use of carbon fiber-reinforced composites as 3D printing materials is remarkable as it improves mechanical properties of the produced parts. Therefore, it is important to find out the positive/negative effects of composite filaments on creep strength. The main purpose of this research is to examine the creep behaviors of PLA and PLA composite produced with 3D printer and to reveal the effects of the printing parameters on the short-term creep. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47564.