Lino Costa, Deepak Rajput, Kathleen Lansford, Wenqiang Yue, Alexander Terekhov and William Hofmeister
The purpose of this paper is to develop a simple, easy to implement powder delivery strategy for solid freeform fabrication (SFF) processing.
Abstract
Purpose
The purpose of this paper is to develop a simple, easy to implement powder delivery strategy for solid freeform fabrication (SFF) processing.
Design/methodology/approach
A specially designed “tower nozzle” located at the center of the processing area dispenses the feedstock powders continuously and uniformly onto the processing area, where powders accumulate progressively as a flat powder bed. During the dispensing, powders are selectively consolidated by melting and solidification using a laser beam which was scanned in a predefined pattern using a galvo‐mirror scan head.
Findings
Experiments performed with AISI H13 steel show that the tower nozzle powder delivery strategy is suitable for SFF processing.
Practical implications
Both powder delivery and laser consolidation are performed simultaneously and without interruption with simple apparatus. No powder delivery scrapers or rollers are used.
Originality/value
The main characteristics of a prototype tower nozzle and the typical processing conditions used to form thin wall AISI H13 steel shapes are presented.
Details
Keywords
Depressive symptoms are higher among racial and ethnic minorities in the United States. Many studies have evidenced associations between school disconnectedness and depressive…
Abstract
Depressive symptoms are higher among racial and ethnic minorities in the United States. Many studies have evidenced associations between school disconnectedness and depressive symptoms by race and ethnicity in adolescence (Joyce & Early, 2014; Walsemann, Bell, & Maitra, 2011). Given that adolescents spend most of their time at home when they are not at school (Larson & Richards, 2001), it is important to understand how mother-child relationships may moderate school disconnectedness, and how mother–child relationships may serve as a protective buffer for depressive symptoms in the transition to adulthood. I use data from Waves II and III of the National Longitudinal Study of Adolescent to Adult Health (Add Health) from 1995 to 2002 (n = 9,766) and OLS regression analysis to examine how school disconnectedness in adolescence is associated with depressive symptoms in the transition to adulthood, and how mother–child relationships in adolescence moderate these associations in the United States. I examine differences in these relationships across racial and ethnic groups. I find that school disconnectedness in adolescence is associated with increased depressive symptoms in the transition to adulthood, and that maternal warmth and communication moderates the association between school disconnectedness and depressive symptoms. Maternal relationship quality in adolescence serves as an important protective factor for mental health in the transition to adulthood.