Effects of Nozzle Design on 3D-Printed UHP-SHCC: Mechanical Performance and Microstructural Insights
The design of extrusion nozzles in 3D concrete printing plays a crucial role in determining the printability and mechanical properties of cementitious composites. Recent industrial and scientific advancements have focused on optimizing nozzle geometry to enhance filament deposition, reduce clogging, and improve overall structural performance. This study investigates rectangular nozzles ranging from 3 mm to 10 mm in thickness and examines their influence on the mechanical behavior of Ultra-High Performance Strain-Hardening Cementitious Composites (UHP-SHCC). Understanding the relationship between nozzle design, fiber alignment, and mechanical performance is critical for advancing 3D concrete printing technology.
Extrudability and Filament Formation
Extrudability is a primary factor in 3D printing performance, and nozzle thickness directly impacts the ease with which UHP-SHCC filaments are deposited. As nozzle thickness decreases, the risk of clogging increases, particularly when fiber content exceeds 2.0 %. Thinner nozzles promote tighter filament formation and better fiber alignment but require careful control of mixture properties to ensure consistent extrusion. The balance between extrudability and filament integrity is vital for achieving high-quality printed structures.
Compressive Strength Variation
The study revealed that nozzle thickness significantly affects compressive strength in multiple loading directions. Perpendicular loading strength increased with thinner nozzles due to denser filament packing and reduced porosity. Longitudinal and lateral compressive strengths were enhanced through combined failure mechanisms at the interface and filament level. This demonstrates that nozzle geometry not only affects the printing process but also the structural capacity of the printed elements.
Tensile Performance and Crack Behavior
Tensile properties of 3D-printed UHP-SHCC improved markedly with thinner nozzles, with tensile strength reaching 9.45 MPa and tensile strain reaching 11.04 %. The failure mode transitioned from quasi-brittle to ductile, accompanied by multiple cracking. The crack pattern shifted from localized to saturated, and crack deflection and twisting further enhanced the flexural properties and toughness of the material. These findings highlight the importance of nozzle design in controlling crack propagation and ductility.
Flexural Behavior and Toughness
Four-point bending tests demonstrated that flexural strength and toughness increased with decreasing nozzle thickness. With thinner nozzles, flexural strength reached 24.69 MPa, and toughness increased to 7117.5 kJ/m³, which were several times higher than mold-cast specimens. These improvements are attributed to improved fiber distribution, crack twisting, and deflection mechanisms, which collectively enhance energy absorption and overall mechanical resilience of the printed structures.
Microstructural Insights via μCT Analysis
Micro-computed tomography (μCT) analysis provided detailed insights into the internal structure of extruded filaments. Thinner nozzles promoted better fiber alignment and reduced porosity, contributing to enhanced strength and ductility. The microstructural improvements explain the observed gains in mechanical performance and support the conclusion that careful nozzle optimization can significantly elevate the quality and durability of 3D-printed UHP-SHCC components.
Architecture Engineers Awards
🔗 Nominate now! 👉 https://architectureengineers.com/award-nomination/?ecategory=Awards&rcategory=Awardee
🌐 Visit: architectureengineers.com
📩 Contact: contact@architectureengineers.com
Get Connected Here:
*****************
Instagram : https://www.instagram.com/architecture_engineers_awards/
Facebook : https://www.facebook.com/profile.php?id=61576995475934
Tumblr : https://www.tumblr.com/blog/architectureengineers
Pinterest : https://in.pinterest.com/
Blogger : https://architectureengineers.blogspot.com/
Twitter : https://twitter.com/
#3DConcretePrinting
#UHP_SHCC
#NozzleDesign
#MechanicalProperties
#Extrudability
#FiberAlignment
#FlexuralStrength
#TensileStrength
#CompressiveStrength
#CrackBehavior
#Ductility
#StructuralEngineering
#ConcreteInnovation
#AdditiveManufacturing
#MaterialScience
#Printability
#MicroCTAnalysis
#ConstructionTechnology
#ToughnessEnhancement
#SustainableConstruction
Comments
Post a Comment