A basic ductile fracture testing program is carried out on specimens extracted from TRIP780 steel sheets including tensile specimens with a central hole and circular notches. In addition, equi-biaxial punch tests are performed. The surface strain fields are measured using two- and three-dimensional digital image correlation. Due to the localization of plastic deformation during the testing of the tensile specimens, finite element simulations are performed of each test to obtain the stress and strain histories at the material point where fracture initiates. Error estimates are made based on the differences between the predicted and measured local strains. The results from the testing of tensile specimens with a central hole as well as from punch tests show that equivalent strains of more than 0.8 can be achieved at approximately constant stress triaxialities to fracture of about 0.3 and 0.66, respectively. The error analysis demonstrates that both the equivalent plastic strain and the stress triaxiality are very sensitive to uncertainties in the experimental measurements and the numerical model assumptions. The results from computations with very fine solid element meshes agree well with the experiments when the strain hardening is identified from experiments up to very large strains.

Hybrid experimental–numerical analysis of basic ductile fracture experiments for sheet metals

Fatigue Fract Eng Mater Struct. 2019;1–17. Abstract For metallic materials, standard uniaxial tensile tests with round bar specimens or flat specimens only provide accurate equivalent stress–strain curve before diffuse necking. However, for numerical modelling of problems where very large strains occur, such as plastic forming and ductile damage and fracture, understanding the post‐necking strain hardening behaviour is necessary. Also, welding is a highly complex metallurgical process, and therefore, weldments are susceptible to material discontinuities, flaws, and residual stresses. It becomes even more important to characterize the equivalent stress–strain curve in large strains of each material zone in weldments properly for structural integrity assessment. The aim of this paper is to provide a state‐of‐the‐art review on quasi‐static standard tensile test for stress–strain curves measurement of metallic materials. Meanwhile, methods available in literature for characterization of the equivalent stress–strain curve in the post‐necking regime are introduced. Novel methods with axisymmetric notched round bar specimens for accurately capturing the equivalent stress–strain curve of each material zone in weldment are presented as well. Advantages and limitations of these methods are briefly discussed.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/ffe.13134

Stress-strain curves of metallic materials and post-necking strain hardening characterization: A Review

Recently, ultra-high strength steel (UHSS) tubes with nominal yield strengths of up to 1200 MPa have attracted attention for applications in engineering fields. While many studies have focused on the mechanical behaviour of mild carbon steel at elevated temperatures, there is a scarcity of data for the in-fire and post-fire mechanical response of the UHSS material. In this study, the tensile mechanical properties of the UHSS tube under fire and after cooling from fire temperatures of up to 800 °C to room temperature are studied. The stress-strain curves, strength and ductility of the UHSS material are discussed. It is shown that the in-fire strength of the UHSS tube starts to deteriorate when the specimens are exposed to fire temperatures above 300 °C and is almost disappeared when tested at 800 °C. There is also a major reduction in the strength of the UHSS tube specimens cooled from fire temperatures above 470 °C to room temperature. To investigate the effect of steel grade on the in-fire and post fire mechanical behaviour of steel materials, the stress-strain curves of Grade 800 high strength steel (HSS) tube specimens are presented and compared with those obtained for Grade 1200 UHSS tube. In order to interpret the experimental results, microstructural examination on the UHSS is conducted using optical and scanning electron microscopy (SEM). The plots of the thermodynamic stability of the ferrite and cementite phases in the UHSS and HSS are calculated and the phase changes occurring during each fire temperature exposure are discussed. Based on the results obtained from experimental tests, an empirical constitutive model which takes into account the post-fire behaviour of UHSS material is developed. The constitutive model can be implemented into commercial finite element packages to carry out a rational thermal analysis and perform fire safety design and evaluation.

Post-fire mechanical response of ultra-high strength (Grade 1200) steel under high temperatures: Linking thermal stability and microstructure

Determination of true stress-strain curve of type 304 and 316 stainless steels using a typical tensile test and finite element analysis

Frosting is a natural phase change phenomenon which happens frequently in nature and industry and has negative effects on a variety of applications. As a passive anti-frosting strategy, superhydrophobic surfaces have been paid more and more attention. To shed light on the process and space–time characteristics of frosting on superhydrophobic surfaces, the preparation methods of superhydrophobic surfaces were introduced first. Then, the internal mechanisms of anti-frosting for superhydrophobic surfaces were revealed from two perspectives of condensation frosting and defrosting. For the preparation of superhydrophobic surfaces, previous studies have shown that laser etching could obtain ideal surface parameters, but there is still a lack of a preparation scheme with low cost and good reliability. For the condensation frosting on superhydrophobic surfaces, the surface with regular surface morphology could realize the spontaneous wettability transformation of the droplets and maintain the size of the condensed droplets within 10–20 μm. The freezing time of droplets on the surface with a regular micro-nano structure is about 4.42 times longer than that on the surface without a regular micro-nano structure. The condensation stage and droplet freezing stage are the keys to preventing frost on superhydrophobic surfaces. For the defrosting on superhydrophobic surfaces, the photothermal defrosting method using metal nanowires, graphene, and carbon nanotubes has a broad application prospect. The results of this study summarized the achievements, problems, and challenges of the current research, so as to provide a reference for the anti-frosting technology of superhydrophobic surfaces in practical applications. 

Review on condensation frosting and defrosting experiments for superhydrophobic surfaces

Large droplets emerging during dropwise condensation impair surface properties such as anti-fogging/frosting ability and heat transfer efficiency. How to spontaneously detach massive randomly distributed droplets with controlled sizes has remained a challenge. Herein, we present a solution called condensation droplet sieve, through fabricating microscale thin-walled lattice structures coated with a superhydrophobic layer. Growing droplets were observed to jump off this surface once becoming slightly larger than the lattices. The maximum radius and residual volume of droplets were strictly confined to 16 μm and 3.2 nl/mm2 respectively. We reveal that this droplet radius cut off is attributed to the large tolerance of coalescence mismatch for jumping and effective isolation of droplets between neighboring lattices. Our work brings forth a strategy for the design and fabrication of high-performance anti-dew materials. 

/pdf/condensation-droplet-sieve-dc1whk9m.pdf

Condensation droplet sieve

Identification of post-necking strain hardening behavior of thin sheet metals from image-based surface strain data in uniaxial tension tests

The liquid barrier is a central component of functional liquid packaging materials and is crucial for encapsulating liquid food. To develop high-performance liquid packaging materials for the long-term storage of liquid food, a strong and stable liquid barrier and the simultaneous integration of diverse functionalities must be realized. In this study, inspired by mussel adhesion proteins, nanoparticles are synthesized through oxidative self-polymerization. Furthermore, electrostatic spinning is used for creating multifunctional electrospun fibers for liquid food packaging, which is inspired by the superhydrophobicity of lotus leaf surface and structures of red blood cells. A unique Janus structure with a thin hydrophilic layer and a thick hydrophobic layer prevents liquid food penetration for 12 (EHN/KN electrospun fibers) and 17 days (KN/EHN electrospun fibers). The liquid infiltration mechanism of Janus electrospun fibers is elucidated using the multibody dissipative particle dynamics method, emphasizing their efficacy in avoiding liquid penetration. Moreover, multifunctional KN/EHN electrospun fibers exhibit remarkable characteristics such as water resistance (water contact angle > 150°), UV-blocking (∼100 %), degradability (70 days in soil), biosafety (∼100 %), antioxidation (> 90 %), antimicrobial (∼100 %), grapes and meat freshness retention properties. Thus, this study provides insights into sustainable, high-performance liquid food packaging for enhanced preservation. 

All-natural and triple-inspired Janus electrospun fibers with integrated functions for high-performance liquid food packaging

Superhydrophobic-Activated Carbon Coating: A Path toward Demulsification and Separation of Crude Oil Emulsions.

Realizing jumping detachment of condensed droplets from solid surfaces at the smallest sizes possible is vital for applications such as antifogging/frosting and heat transfer. For instance, if droplets uniformly jump at sizes smaller than visible light wavelengths of 400-720 nm, antifogging issues could be resolved. In comparison, the smallest droplets experimentally observed so far to jump uniformly were around 16 μm in radius. Here, we show molecular dynamics (MD) simulations of persistent droplet jumping with a uniform radius down to only 3.6 nm on superhydrophobic thin-walled lattice (TWL) nanostructures integrated with superhydrophilic nanospots. The size cutoff is attributed to the preferential cross-lattice coalescence of island droplets. As an application, the MD results exhibit a 10× boost in the heat transfer coefficient (HTC), showing a -1 scaling law with the maximum droplet radius. We provide phase diagrams for jumping and wetting behaviors to guide the design of lattice structures with advanced antidew performance.

Uniform and Persistent Jumping Detachment of Condensed Nanodroplets.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Lin Wang

Author Tools

Chat about Author