Bernard Rolfe

Design and experimental validation of self-supporting topologies for additive manufacturing

Publisher: Informa UK Limited

Date: 24-07-2019

DOI: 10.1080/17452759.2019.1637023

3D-Printed Programmable Mechanical Metamaterials for Vibration Isolation and Buckling Control

Publisher: MDPI AG

Date: 02-06-2022

DOI: 10.3390/SU14116831

Abstract: Vibration isolation performance at low-frequency ranges before resonance is a vital characteristic that conventional springs cannot exhibit. This paper introduces a novel zero Poisson’s ratio graded cylindrical metamaterial to fulfill two main goals: (1) vibration isolation performance in low-frequency bands prior to resonance and (2) global buckling control of a long cylindrical tube. For this purpose, “soft and stiff” re-entrant unit cells with varying stiffness were developed. The cylindrical metamaterials were then fabricated using a multi-jet fusion HP three-dimensional (3D) printer. The finite element analyses (FEA) and experimental results demonstrate that the simultaneous existence of multi-stiffness unit cells leads to quasi-zero stiffness (QZS) regions in the force-displacement relationship of a cylindrical metamaterial under compression. They possess significant vibration isolation performance at frequency ranges between 10 and 30 Hz. The proposed multi-stiffness re-entrant unit cells also offer global buckling control of long cylindrical tubes (with a length to diameter ratio of 3.7). The simultaneous existence of multi-stiffness re-entrant unit cells provides a feature for designers to adjust and control the deformation patterns and unit cells’ densification throughout cylindrical tubes.

Development of a reversible top-hat forming approach for reducing flange wrinkling in flexible roll forming

Publisher: Elsevier BV

Date: 08-2023

DOI: 10.1016/J.IJMECSCI.2023.108359

Springback Investigation in Roll Forming of a V-Section

Publisher: Trans Tech Publications, Ltd.

Date: 05-2014

DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.643

Abstract: To have fuel efficient vehicles with a lightweight structure, the use of High Strength Steels (HSS) and Advanced High Strength Steels (AHSS) in the body of automobiles is increasing. Roll forming is used widely to form AHSS materials. Roll forming is a continuous process in which a flat strip is shaped to the desired profile by passing through numerous sets of rolls. Formability and springback are two major concerns in the roll forming of AHSS materials. Previous studies have shown that the elastic modulus (Young’s modulus) of AHSS materials can change when the material undergoes plastic deformation and the main goal of this study is to numerically investigate the effect of a change in elastic modulus during forming on springback in roll forming. Experimental loading-unloading tests have been performed to obtain the material properties of TRIP 700 steel and incorporate those in the material model used in the numerical simulation of the roll forming process. The finite element simulations were carried out using MSC-Marc and two different element types, a shell element and a solid-shell element, were investigated. The results show that the elastic modulus diminution due to plastic strain increases the springback angle by about 60% in the simple V-section roll forming analyzed in this study.

Constitutive modelling of high strength titanium alloy Ti-6Al-4 V for sheet forming applications at room temperature

Publisher: Elsevier BV

Date: 02-2016

DOI: 10.1016/J.IJSOLSTR.2015.08.025

Analysis of Acoustic Emissions for Determination of the Mechanical Effects of Scratch Tests

Publisher: MDPI AG

Date: 02-07-2022

DOI: 10.3390/APP12136724

Abstract: Acoustic Emission (AE) is a promising technique for measuring tool wear online and in real time. In this work, scratch tests were conducted to better understand the “pre-wear” AE response based on loading conditions that were not sufficient to generate galling. The scratch tests used the same type of indenter against two different sheet materials: aluminum and steel. The results showed that AE parameters such as the mean frequency, Centroid frequency and Shannon entropy outperformed other frequency domain techniques by discriminating between the two sheet materials in scratch tests. From the literature, the frequency region of interest was expected to be sub 300 kHz. However, in this study, activity below this threshold was found to be noise, whereas distinct frequencies were found at much higher frequencies than expected. These results are compared against single grit “SG” tests of both mild steel- and nickel-based superalloys to allow comparison of the two test methods and materials used. This comparison showed that the SG tests excited the acoustic emission in ways in which the scratch tests did not. Another factor when using acoustic emissions to monitor sheet metal forming is the differences obtained in energy–frequency mapping, where many report the galling phenomena between a certain litude and frequency range. Such results are specific to the setup and the materials/geometries used. Further work presented here compares different scratch tests where energy–frequency mapping is different for different materials/geometries.

Effect of stiffness anisotropy on topology optimisation of additively manufactured structures

Publisher: Elsevier BV

Date: 09-2018

DOI: 10.1016/J.ENGSTRUCT.2018.05.083

Tool Wear in Sheet Metal Stamping

Publisher: Trans Tech Publications, Ltd.

Date: 12-2011

DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.421.750

Abstract: This paper discusses our recent research on wear at the die radius in sheet metal st ing. According to wear theory, contact pressure and sliding distance are the two dominant factors in determining sliding wear. We applied the finite element analysis to accurately quantify the contact pressure and sliding distance at the die radius in sheet metal st ing. The results were then applied to analyze sliding wear at the die radius. We found that a typical two-peak steady-state contact pressure response exists during a channel forming process. The steady-state contact pressure response was preceded by an initial transient response, which produced extremely large and localized contact pressures. We proposed a method to numerically quantify the sliding distance, which was applied to examine the contact sliding distance at the die radius. Correlating the contact pressure and sliding distance, a new insight into the wear/galling that occurs at the die radius in sheet metal st ing was gained. The results show that the region close to zero degrees on the die radius is likely to experience the most wear, with the identified transient stage contributing to a large proportion of the total wear.

Parametric studies and manufacturability experiments on smooth self-supporting topologies

Publisher: Informa UK Limited

Date: 23-07-2019

DOI: 10.1080/17452759.2019.1644185

Smooth Design of 3D Self-Supporting Topologies Using Additive Manufacturing Filter and SEMDOT

Publisher: MDPI AG

Date: 29-12-2020

DOI: 10.3390/APP11010238

Abstract: The smooth design of self-supporting topologies has attracted great attention in the design for additive manufacturing (DfAM) field as it cannot only enhance the manufacturability of optimized designs but can obtain light-weight designs that satisfy specific performance requirements. This paper integrates Langelaar’s AM filter into the Smooth-Edged Material Distribution for Optimizing Topology (SEMDOT) algorithm—a new element-based topology optimization method capable of forming smooth boundaries—to obtain print-ready designs without introducing post-processing methods for smoothing boundaries before fabrication and adding extra support structures during fabrication. The effects of different build orientations and critical overhang angles on self-supporting topologies are demonstrated by solving several compliance minimization (stiffness maximization) problems. In addition, a typical compliant mechanism design problem—the force inverter design—is solved to further demonstrate the effectiveness of the combination between SEMDOT and Langelaar’s AM filter.

Anisotropic plasticity and fracture modelling of cold rolled AA5754

Publisher: Elsevier BV

Date: 09-2023

DOI: 10.1016/J.ENGFRACMECH.2023.109471

Plastic instability and fracture of ultra-thin stainless-steel sheet

Publisher: Elsevier BV

Date: 10-2020

DOI: 10.1016/J.IJSOLSTR.2020.06.029

Friction and Wear in Stages of Galling for Sheet Metal Forming Applications

Publisher: MDPI AG

Date: 07-07-2023

DOI: 10.3390/LUBRICANTS11070288

Abstract: Aluminum is a very commonly used material at present, and roughly half of the produced aluminum products undergo forming during manufacturing. Galling is a severe form of wear that occurs during sheet metal forming operations and is a common failure mode of materials in sliding contact however, the causes and mechanisms of galling are poorly understood. In this work, sliding wear experiments were conducted to produce galling wear between a tool steel ball bearing and aluminum alloy Al5083, to study the relationship between the coefficient of friction, the lump growth on the tool and the scratch morphology. Whilst the characteristic friction regimes were observed, the characteristic damage (grooves running parallel to the scratch direction) was not observed. Instead, when galling was developed on the indenter, the scratch surface morphology displayed a series of peaks and grooves perpendicular to the scratch direction. It is likely that the difference in scratch morphology observed once galling was initiated is due to the lower hardness and reduced work hardening behavior of the Al5083 alloy, compared to the high strength steels previously examined in sheet metal forming applications. The evolution of the scratch morphology has been characterized in a novel way by investigating the distribution of the longitudinal cross-section profile height along the scratch length in relation to the three-stage friction regime observed. This showed that, as the galling wear progressed, the longitudinal cross-section profile height distribution shifts towards negative values, with a corresponding shift in the distribution of material transferred to the tool shifting to the positive. This indicates that, as the amount of material adhered to the indenter increased, the depth of the grooves on the scratch surface perpendicular to the sliding direction also increased.

Finite Element Analysis of Residual Stresses in Metallic Coatings through a Compound Casting

Publisher: Trans Tech Publications, Ltd.

Date: 05-2014

DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.48

Abstract: Al and Mg alloys are widely used in industry as main lightweight alloys. They have excellent properties, such as low density, high ductility, and high specific strength, and so on. Generally speaking, Mg alloys are better than Al alloys. However the corrosion of Mg alloys is much more difficult to control compared Al alloys. Therefore to combine these two lightweight alloys, a composite-like structure is an ideal solution since Al alloys can be used as protective coatings for Mg alloys. Compound casting is a realistic technique to get this coating system. In the current study, we numerically study the compound casting using finite element method (FEM) to make these two alloys, a composite-like structure, satisfy requirements to resist corrosion required from industry, in which the aluminum layer is acting as a protective coating for the magnesium substrate. Several finite element models have been developed by using the birth and death element technique and we focus on compound casting-induced residual stresses in the compounded structure. The numerical results obtained from the proposed finite element models show the distribution profiles of thermal residual stresses. We found the major factors influencing the residual stresses are the temperature to pre-heating the Al substrate and the thickness of Mg deposits.

Sandwich structure printing of Ti-Ni-Ti by directed energy deposition

Publisher: Informa UK Limited

Date: 18-07-2022

DOI: 10.1080/17452759.2022.2096647

Topology Optimisation of Structural Steel with Non-Penalisation SEMDOT: Optimisation, Physical Nonlinear Analysis, and Benchmarking

Publisher: MDPI AG

Date: 17-10-2023

DOI: 10.3390/APP132011370

4D printing soft robots guided by machine learning and finite element models

Publisher: Elsevier BV

Date: 09-2021

DOI: 10.1016/J.SNA.2021.112774

Australian National University

Location: Australia

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Deakin University

Location: Australia

View Organisation

Flexible Forming Facility For Low Cost Light Weight Applications

Start Date: 2014

End Date: 2014

Funder: Australian Research Council

Spark Plasma Sintering (SPS) Facility For Advanced Materials Processing

Start Date: 2009

End Date: 2009

Funder: Australian Research Council

High Rate Testing System For Materials And Structures

Start Date: 2007

End Date: 2007

Funder: Australian Research Council

Direct Metal Deposition Freeform Fabrication Facility For Rapid Tooling And Manufacturing

Start Date: 2006

End Date: 2006

Funder: Australian Research Council

Design Strategy For Cold Roll Formed Products

Start Date: 2008

End Date: 2011

Funder: Australian Research Council

Developing An Environmentally Friendly, Low Cost Solution To Reduce Wear And Improve Productivity In Metal Forming

Start Date: 2012

End Date: 2014

Funder: Australian Research Council

Dimensional Control Of Stamped Components For Optimized Assembly Operations

Start Date: 2005

End Date: 2007

Funder: Australian Research Council

Reducing Tool Wear Through Novel Surface Treatments And Improved Lubrication

Start Date: 2007

End Date: 2010

Funder: Australian Research Council

Nodal Power Saving For Disconnected Ad Hoc Sensor Networks

Start Date: 2006

End Date: 2008

Funder: Australian Research Council

Developing Light Weight Automotive Structures

Start Date: 2004

End Date: 2008

Funder: Australian Research Council

Developing Intelligent Systems For Manufacturing Control

Start Date: 2004

End Date: 2006

Funder: Australian Research Council

Hybrid Testing Facility For Structures Under Extreme Loads

Start Date: 2011

End Date: 2011

Funder: Australian Research Council

Dynamic Texture Measurement Facility

Start Date: 2009

End Date: 2009

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0776913

Start Date: 02-2008

End Date: 12-2011

Amount: $405,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP150100059

Start Date: 12-2015

End Date: 12-2019

Amount: $210,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0883399

Start Date: 12-2008

End Date: 12-2012

Amount: $225,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP120100239

Start Date: 11-2012

End Date: 12-2016

Amount: $409,967.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP120100111

Start Date: 11-2012

End Date: 12-2018

Amount: $270,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0775656

Start Date: 2007

End Date: 12-2007

Amount: $490,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989123

Start Date: 12-2009

End Date: 12-2010

Amount: $575,000.00

Funder: Australian Research Council

Industrial Transformation Research Hubs - Grant ID: IH130100008

Start Date: 03-2015

End Date: 02-2021

Amount: $4,000,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0667181

Start Date: 01-2006

End Date: 12-2010

Amount: $250,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0455249

Start Date: 03-2005

End Date: 12-2010

Amount: $596,039.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0560908

Start Date: 2005

End Date: 12-2009

Amount: $312,198.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP230100995

Start Date: 2023

End Date: 12-2025

Amount: $490,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668473

Start Date: 2006

End Date: 12-2006

Amount: $710,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0450671

Start Date: 04-2004

End Date: 07-2007

Amount: $180,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP200100265

Start Date: 11-2021

End Date: 11-2024

Amount: $269,521.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE220100150

Start Date: 08-2022

End Date: 07-2023

Amount: $320,000.00

Funder: Australian Research Council

Industrial Transformation Training Centres - Grant ID: IC160100032

Start Date: 06-2017

End Date: 06-2023

Amount: $3,024,379.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100052

Start Date: 07-2011

End Date: 2015

Amount: $870,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100003

Start Date: 06-2014

End Date: 06-2015

Amount: $280,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989492

Start Date: 2009

End Date: 01-2010

Amount: $350,000.00

Funder: Australian Research Council