bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Self Compacting Geopolymer Concrete (SCGC) haunch beams at monotonic loading and loading-unloading scheme
Authors: Purwanto  , Nuroji  , Ekaputri Januarti Jaya , Indriyantho Bobby Rio , Riko Rydell
Published: June 2023

Numerous reinforced concrete structures require strengthening due to mistakes in detail engineering design, incorrect execution during construction, or overloading. One method of structural strengthening is to use haunch beam casted near column. The development of infrastructure in Indonesia leads to an increase in cement use. This phenomenon causes a greenhouse effect due to higher CO2 emissions, so that an effort is performed in order to reduce the use of cement concrete by using geopolymer concrete. This study aims to experimentally analyze the behavior of haunch beams using both Self-Compacting Geopolymer Concrete (SCGC) and conventional Self-Compacting Concrete (SCC) in terms of load and deflection at first crack, yield, and ultimate conditions as well as crack pattern and plastic hinge of the beam. This study utilized four specimens consisting of SCGC and SCC haunch beams with a compressive strength fc’ of 31 MPa. All identical specimens were tested at monotonic loading and loading-unloading conditions. As a result, the haunch beams due to monotonic loading have larger load capacity and deflection compared to the haunch beams due to loading-unloading. The SCGC haunch beam has slightly lower load capacity and smaller deflection compared to the SCC haunch beam. This shows the SCGC performance is relatively similar to that of the SCC. The SCGC can substitute the SCC, especially for structural reinforcements. Due to monotonic loading and loading-unloading state, both the SCGC and the SCC haunch beams were plasticized at the same location at the haunch end. By implementing the haunch beams, plastic hinges move away from the column.
Flexural strength and drift ratio of reinforced concrete beams with longitudinal square hole
Authors: Sumiati  , Wibowo Leonardus Setia Budi
Published: June 2023

The main aim of this investigation was to study the flexural strength and drift ratio of simply supported rectangular RC hollow beams (with a longitudinal square hole) subjected to gradually increased and symmetrically applied one-point load. Each hollow beam had a 300 mm2 and 900 mm2-area of a square, and the position of the center of the hole was 80 mm from the top. The cross-section of the beam, the amount of longitudinal steel, and the stirrups of the beam was kept constant. The flexural strength and deflection of these hollow beams were compared with that of a solid RC beam that had the same outer dimensions and steel reinforcements. A comparison of experimental results shows that specimens with square holes 10 x 30 achieve higher peak load, MOE, and MOR. On other hands, solid beam specimens achieve a larger drift ratio.
Structural evaluation of existing buildings using surface ground motions
Authors: Partono Windu
Published: June 2023

Research on new seismic sources and seismic data has already performed in 2016 to 2017. Four new shallow crustal fault sources were observed surrounding the city of Semarang, the capital city of Central Java Province, Indonesia. The seismic parameters related with the seismic mechanism (reverse fault) and the maximum magnitude prediction (6.5 Mw) for each seismic sources was also released based on the 2017 research. Following this research, structural evaluation especially for buildings that was designed and constructed based on 2002 Indonesian Seismic Code was also performed. The spectral acceleration design of 2002 seismic code was developed based on subduction source located at the southern of Java island. The structural evaluation was performed for all university buildings located at the Diponegoro University. This paper describes the seismic hazard analysis results of the university area and an example results of building evaluation located at this area. The seismic hazard analysis was performed based on the 2002 Probability Seismic Hazard Analysis/PSHA of the code and the Deterministic Seismic Hazard Analysis (DSHA) of four seismic sources. Two different structural analysis were conducted for all buildings such as structural deformation and drift ratios. Based on the seismic hazard analysis results, all buildings located at the university area were strong enough in resisting the surface ground motion (Peak Ground Acceleration/PGA) due to shallow crustal fault earthquake scenarios having magnitude 6.5 Mw. The buildings deformation and drift ratios calculated using 2002 Indonesian seismic code are greater compared to the same analysis calculated based on deterministic model of shallow crustal fault sources.
Nonlinear analysis of interior and exterior beam-column connections under reversed cyclic loading
Authors: Tambusay A , Suryanto B , Suprobo P , Nelson JJM
Published: June 2023

This paper presents a case study into the application of nonlinear finite element for the analysis of interior and exterior beam-column joints under reversed cyclic loading. Three beam-column joints, with different reinforcement configurations and test conditions, were considered to assess the accuracy of the currently available constitutive models in predicting the full hysteretic response of beam-column joints under reversed cyclic loading. To this end, the three beam-column joints were modelled in ATENA-GiD which implements nonlinear constitutive models for steel and concrete, the latter of which are formulated within the context of crack-band and crush-band approaches. In this paper, the default constitutive models in the program were employed to evaluate the accuracy of the existing modelling and analysis procedures. From the series of results presented, it is shown that the existing constitutive models are capable of predicting various aspects of the joint behaviour under reversed cyclic loading with good accuracy. This includes the peak load capacity, degrees of pinching and strength degradation, strength and stiffness degradation, unloading and reloading stiffnesses, crack patterns and failure modes.
Applying moment redistribution and externally bonded FRP in beams for seismic strengthening of RC frames
Authors: Utomo Junaedi , Jati Dinar Gumilang , Tanudjaja Felix Adi , Lie Han Ay
Published: June 2023

The approach for seismic strengthening of RC frames using moment redistribution and externally bonded FRP is especially applicable for enhancing the performance of a building that is designed prior to the introduction of the new seismic codes. The design and detailing requirements for these building categories were conducted following the capacity design principle. Based on the more recent codes, these buildings are under-designed, and seismic strengthening has become mandatory. Additionally, the buildings might need to be strengthened to fulfill the stringency design requirements of modern seismic building codes. The moment redistribution theory is based on the principles of transferring a moment to sections with lower stresses when the peak moment reaches the ultimate capacity of the section. The redistribution of moments has to be established before all the critical sections can attain their ultimate flexural strength. FRP materials are characterized by their high strength and lightweight. Externally bonded FRP is relatively cost-effective, less invasive, and easily implementable because of the minimal surface preparation. Apart from the moment capacity increase, externally bonded FRP could also improve the shear capacity at critical sections through confinement to an area within the boundaries of the FRP.
Evaluation of bonding performance of ultra high-performance concrete with fly ash content as overlay on normal strength concrete.
Authors: Kuncoro A , Pranoto H D , Sacca L W , Antoni A , Hardjito D , Tanojo E
Published: June 2023

Ultra High-Performance Concrete (UHPC) has good mechanical strength and durability, so it can be the solution for an overlay material for old materials that need to be renewed. The problem with using UHPC as a construction material is the high price and sustainability, so a partial replacement for cement is required to reduce production costs, energy consumption, and CO2 gas emissions. Bonding performance is an important parameter and must be considered when applying UHPC as an overlay material. The bonding performance test of the UHPC consists of three tests: the slant shear test, splitting tensile, and direct tensile/pull-off test. The results of this study were compared with the standards of ACI 546R-14 and M.M. Sprinkel & C. Ozyildirim. Based on the test results, replacing 40% of cement with fly ash on UHPC is good to use as an overlay because it meets applicable standards. The test results showed an increase of 27% in the slant shear test and 37% in the splitting tensile test compared to the existing standard. Replacing cement with fly ash in UHPC can also increase workability, reducing the need for superplasticizers, reducing UHPC production costs by 18.4%, energy consumption, and CO2 emission problems.
Stiffness modulus of reclaimed asphalt binder modified with local bio-rejuvenator in Indonesia (dynamic shear rheometer to van der poel nomograph test result)
Authors: Sihombing Atmy Verani Rouly , Subagio Bambang Sugeng , Hariyadi Eri Susanto , Sihombing Reza Phalevi
Published: June 2023

This study intends to examine the effect of using bio-rejuvenators (BioCS and BitutechRAP) on Reclaimed Asphalt (RA) binder as seen from the asphalt binder stiffness modulus (Sbit) based on laboratory testing using Dynamic Shear Rheometer (DSR) Frequency Sweep which is compared to Sbit resulting from analysis using Van der Poel nomograph under RTFO (rolling thin film oven) conditions. The comparison was analyzed by looking at the adjustment factor produced from each type of asphalt binder testing. The types of asphalt binders tested were pen 60/70 as control asphalt binder, 23% BioCS mixed in RAbinder, and 17% BitutechRAP mixed in RA binder. The results showed that the Sbit value from the DSR and Van der Poel test results was not too much different, with an adjustment factor of 1.61, the addition of BioCS to the RA binder was more influential than BitutechRAP, this was indicated by the adjustment factor of the BioCS + RA binder value of 2.84 which is close to the pen 60/70 adjustment factor value of 2.64.
The effect of polypropylene fiber on the mechanical properties between hybrid fiber geopolymer concrete and geopolymer concrete in elevated temperature
Authors: Farida F M , Hardjasaputra H , Surahman A , Sofwan A , Mukti R R
Published: June 2023

This paper has influence on discovering the behavior of hybrid polypropylene fiber reinforced geopolymer concrete under constant and elevated temperature with the purpose to determine the mechanical properties of the material. While the expertise and acquaintance with concrete behavior under constant temperature are well known, the behaviour under elevated temperature has to be seriously explored. This study objectives is to match between the mechanical properties of unburnt and burnt fiber reinforced geopolymer concrete. This study uses experimental investigation. Compression and splitting tensile tests were conducted on the 150 mm cilinder mold. Meanwhile, flexural tension test was conducted on 100 mm x 100 mm x 450 mm rectangular mold. The result of both materials, without set fire to and with set fire to, are analyzed. The gained findings for burnt material are the compression test value cut down, otherwise, the splitting tensile test and flexural tensile strength grade increase.
The influence of calcium oxide doses as an activator on the compressive strength and mechanical characteristics of cement-free mortar containing ground granulated blast furnace slag
Authors: Djayaprabha Herry Suryadi , Hermawan
Published: June 2023

In the construction industry, cement-based materials as aggregate binding agent are still widely used. Due to the environmental concern, researchers are working to create eco-friendly cement-free binding materials. Calcium oxide (CaO) is a reactive earth metal oxide that could serve as a potential activator for ground granulated blast furnace slag (GGBFS). In this experimental study, the cement-free mortar was produced by using GGBFS as the base material and CaO as an activator with varied doses of 5%, 15%, and 25% with a fixed water-to-binder ratio (w/b) of 0.4. The results showed that the 28-day compressive strength values of the mixture with an amount of CaO of 5%, 15%, and 25% were 21.45, 32.03, and 25.80 MPa. Moreover, the values of bulk density and porosity of free-cement mortar at the age of 28 days ranged between 1.932 - 1.939 g/cm3 and 22.66% - 24.95%, respectively. According to the research findings, the optimal additional CaO amount of 15% exhibited the series’ highest compressive strength and lowest porosity.
Compressive strength, porosity, and density of mortar containing precipitated silica from Palm Oil Fuel Ash (POFA)
Authors: Olivia Monita , Wibisono Gunawan , Utama Panca Setia , Supit Steve
Published: June 2023

Palm Oil Fuel Ash (POFA) as an agro-industrial waste has potential applications in the construction industry. Using POFA to produce extracted precipitated silica is another step toward improving the performance of mortar and concrete with cost-effective biomass waste. This study investigates precipitated silica extracted from POFA as an additive for mortar. Mortar mixtures containing various percentages of precipitated silica (PS) and silica fume (SF) with 2%, 4%, and 6% by weight of cement were cast and studied. Compressive strength, porosity and density of the mortar at 28 days were tested to study the physical properties of the PCC-SP and PCC-SF mortars. The compressive strength of PCC-PS and PCC-SF mortars increased with the optimum 4% addition of silica. Precipitated silica mortar (PCC-PS) has lower strength, higher porosity, and similar density to the silica fume mortar (PCC-SF). However, the precipitated silica mortar has better strength, porosity, and density than the PCC mortar (control mix). The current findings suggest that the extracted precipitated silica can be used as a cost-effective additive from biomass waste to improve the performance of mortar and concrete.
The Use of Cationic Rapid Setting Emulsion Cold Asphalt Mixtures for Appropriate Road Rehabilitation
Authors: Setyawan A , Habiburrahman M , Sarwono D , Suryoto  , Rifai M , Budiarto A
Published: June 2023

This study aims to determine the Optimum Residual Asphalt Content in different aggregate sources and the characteristics of Cold Emulsion Asphalt Mixture if the gradation used is the National Asphalt Pavement Association (North Carolina) gradation. The aggregates used in this study came from PT. Pancadarma Puspawira, Surakarta and The Public Work Office Magetan District with the asphalt used is cationic emulsion asphalt type CRS-2. The emulsified asphalt content used for the Magetan mixture was 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, while the emulsified asphalt content for the Pancadarma mixture was 7.5%, 8.0%, 8.5%, 9.0%, 9.5%. The parameters reviewed in this study were density, VIM, VMA, VFB, stability, flow and Marshall Quotient with reference to the 2018 Highways Specification for repair overlay. The results showed that the emulsified asphalt mixture of CRS-2 Magetan and Pancadarma did not meet the specifications for repair overlay. The optimum emulsion asphalt content that is possible in the Magetan mixture is 8.0% with KARO 5.37% (stability 269.24 kg; density 2.04 gr/cc; VIM 5.71%; MQ 65.28 kg/mm; Flow 4.31 mm; VMA 18.39%; VFB 68.95 %). While the Pancadarma mixture is 9.5% with KARO (stability 70.07 kg; density 2.22 gr/cc; VIM 4.75%; MQ 23.31 kg/mm; Flow 3.05 mm; VMA 23.79%; VFB 80.03%).
Experimental study on foam concrete as a sub-base layer of rigid pavement
Authors: Harnedi Raihan Arditama , Rahman Harmein , Maizir Harnedi
Published: June 2023

Rigid pavement consists of three main layers, the base, sub-base and subgrade. Engineers mainly prefered choosing rigid pavement for heavy load road construction because the concrete mixture in this type of pavement has advantages in terms of strength, durability and design life. However, rigid pavement also has several disadvantages: relatively high construction and maintenance costs. As time goes by, researchers have developed several modified concrete mixtures; one of them is foam concrete. Foam concrete has strength similar to concrete in general but with a lighter mass and more affordable construction cost. This study examines foam concrete’s mechanical properties and properness as a sub-base layer on a rigid pavement. The research was conducted experimentally in the lab with five different densities of foam concrete mixture. The results showed that sample with a density of 1.0 g/cm3 has passed the minimum compressive and flexural strength values at 0.896 MPa and 0.0059 MPa respectively. This also indicates that increasing the density of a foam concrete mixture may increase its compressive and flexural strength but also lose its advantage of being a lightweight material as more density means more weight. Thus, it can be concluded that using foam concrete as a sub-base layer of rigid pavement is more advantageous in implementing rigid pavement construction.
The quality assurance factors that affect the product quality performance: A case of the building X construction project in Jakarta
Authors: Sihombing Lukas B. , Sumurung George A.
Published: June 2023

Quality is a goal in a project in addition to cost and time. The quality assurance program of a project functions to ensure that the process during the production period reaches the agreed upon quality targets. The finding of product defects in a building X construction project in Jakarta is the background of this research. The purpose of this study is to identify the quality assurance factors on the product quality performance, analyze the quality assurance factors on the product quality performance, and identify the quality assurance factors that contribute to the product quality performance in a building X construction project in Jakarta. The research methodology was quantitative in nature, starting by identifying the quality assurance factors through a literature study, validating the factors with expert respondents, conducting a survey by distributing questionnaires to respondents, and analyzing the survey results. From the results of this study, six quality assurance factors were found to affect the product quality performance of a building X construction project in Jakarta, namely monitoring and evaluating the work instruction procedure processes, having documents containing quality requirements set by the company and national/international quality standards, conducting quality assurance training programs for the staff, making recommendations for product improvements in project quality information reports, and establishing criteria for the production process.
A conceptual framework for integrating QSHE in construction
Authors: Silalahi Andreas Partogi , Widjajakusuma Jack , Tanuhendrata Michael Sofian , Suraji Akhmad
Published: June 2023

Construction accidents become catastrophic in infrastructure development. Evidence shows that quality failures such as system, services, procedural, materials, equipment, and human failures within the business process of project delivery systems are contributing causes of construction accidents that negatively impact worker safety, public safety, building/asset, and environmental safety. The standardized quality management systems and safety management systems in construction are fragmented. The Indonesian authorities have integrated the Quality Safety Health and Environment (QSHE) management system since 2018, but the implementation of the integrated QSHE system is still questionable. This paper aims to propose a framework and methodology for integrating QSHE implementation. The framework is based on the literature review of international standards and the UK Construction Design & Management Regulation. This proposal is a part of research currently formulated to develop an operating system to integrate quality and construction safety best practices in the project delivery systems. This paper addresses the quality management framework, safety management framework and, the proposed conceptual framework for integrating quality and safety management systems. The development of an integrated QSHE management system has the potential to save resources and eliminate redundancy significantly. Thus, an organization’s net production, profitability, and efficiency can significantly be increased. The results of this paper are 51 key points that are needed for integrating QSHE in construction projects. In the pre-construction stage, there are 24 key points, which are the largest portion. During the construction stage, there are 19 key points, and during the post-construction stage, there are 8 key points. So, it is very important to carry out the QSHE integration during the pre-construction stage to minimize the defects and accidents in construction projects.
Integrated analysis approach to structure PPP schemes for new infrastructure projects
Authors: Onishi T , Miyamoto K
Published: June 2023

When considering public–private partnerships (PPP) for new infrastructure development, it is necessary to structure a project scheme based on the financial analyses from the perspective of private businesses, bankability analyses of private finances from the perspective of lenders, and public expenditure analyses from the viewpoint of the public sector after satisfying the criteria of the economic analysis from the viewpoint of the national economy. Although these four analyses are closely related, it is difficult to structure a scheme from a comprehensive viewpoint because they are typically implemented individually. Therefore, this paper proposes an analytical approach that integrates economic, financial, bankability, and public expenditure to conduct a comparative evaluation of various business schemes, including PPP. First, the basic idea of an integrated analysis was explained in detail. After developing each analysis table on a spreadsheet, an integrated analysis table was derived by interconnecting the tables. In addition, using an integrated analysis table prepared for a virtual new toll road project, the usefulness of the integrated analysis approach for structuring the project scheme was confirmed through case studies.
Stakeholders’ readiness in implementing regulation on affordable public housing: a case study in Pemalang Regency, Central Java
Authors: Hermawan F , Prihantini A D , Suliantoro H
Published: June 2023

The lengthy licensing stage is becoming a problem in low-income housing development. Stakeholders’ readiness plays an essential role in the success factor of low-income housing. This study aims to identify the stakeholders’ readiness for regional autonomy in terms of policy implementation according to the Regulation of the Minister of Home Affairs Number 55 of 2017 concerning Low-Income Housing in Pemalang Regency. The research method adopted the policy model by Edwards III and the analytical hierarchy process (AHP). The determination of the criteria in this study was divided into four criteria: communication (human and financial) resources, implementers’ disposition/behaviour, and bureaucratic structure. These four criteria were analysed using the AHP method on eight respondents from one of the institutions related to the licensing stage. The findings suggested five strategies that could improve programs to accelerate the provision of low-income housing. The order of priority for those five strategies is: (1) capacity building of local authority staff; (2) improvement of the bureaucratic system and licensing services; (3) sanctions for parties affecting the licensing service process; (4) provision and dissemination of information; and (5) revision of regulations (Regulation of the Minister of Home Affairs).
Accessible pedestrian paths for educational setting design evaluation: Case study in Surabaya and Bandung City, Indonesia and Brisbane City, Australia
Authors: Tallar Robby Yussac , Tanuwidjaja Gunawan , Widjaya Joyce Martha , Razafimahefa Rina
Published: June 2023

Covid-19 has changed the city and human lives, especially related to walking. The lockdowns in several countries such as China, Japan and Australia have prescribed urban residents to stay within approximately five to ten kilometres radius of their homes. The lockdowns were found helpful in suppressing the Covid-19 spread at a local level. However, more discussions are needed on the well-being and health of residents during a hard time. In Australia, two people could exercise during lockdowns for one hour within the resident’s neighbourhoods. The needs for accessible pedestrian paths in the neighbourhood are essential during Covid-19. Some universities were closed during the lockdowns in the educational sector, but students could stay near the campus and use facilities within. Many students need accessible pedestrian paths to walk to the campus from their apartments and shopping centres. This lockdown further generates the idea to research pedestrian paths’ accessibilities in some educational context in Surabaya, Bandung, both in Indonesia and Brisbane, Australia. The simple access evaluations are conducted with photography documentation and simple measurement based on ADAAG 2010 and local regulations. Therefore, the pedestrian paths in two locations in Indonesia are found to be less accessible, while pedestrian paths in Brisbane are found to be more accessible. The less accessible Indonesian pedestrian paths are caused by a lack of spaces, poor construction, and pedestrian paths’ poor management. Meanwhile, better access standards, better infrastructure management, and proper construction are essential key points for better accessible pedestrian paths.
Effect of bed shear stress on the mobile armor layer at the riverbed
Authors: Negara Arlendenovega S , Ikhsan Cahyono , Hadiani Rr. Rintis , Purwana Yusep M
Published: June 2023

Armoring is forming an armor layer of the riverbed which is preceded by the transportation of bed sediment. Mobile armor occurs when the riverbed reaches equilibrium, then eroded, and the surface of the riverbed recovers. Therefore, protection is formed by moving riverbed material. This research used a simulation model generated through HEC RAS software version 6.1. The model input location was Krasak River, Sleman, Yogyakarta. The data for model input were the topography of the Krasak River from upstream to the point of view, flood discharge hydrograph, and grain size gradations. The simulation combination consisted of three locations with the riverbed material of each location sampled tested for grain size distribution. The running simulations combined the flood discharge at return periods of 2, 5, 10, 25, 50, and 100 years. There were three variations of grain size distribution used as input data. Meanwhile, variations of sediment transport methods used the Meyer-Peter Muller and Wilcock-Crowe methods. Overall, the simulation results show that the shear stress and the proportion of sand-to-grain material affect the armoring process and riverbed changes.
A mechanical interlocking joint between sheet metal and carbon fibre reinforced polymers through punching
Authors: Latorre Núria , Casellas Daniel , Costa Josep
Published: June 2023

The joint between different lightweight materials plays a significant role in multi-material design of structural components for the automotive industry, aiming to reduce the vehicle’s weight without compromising performance or safety. Yet, conventional mechanical joining technologies between metals and Carbon Fibre Reinforced Polymers (CFRP) result in either a hole being drilled in the composite material, leading to damages which reduce the load bearing capacity, or the weight of the part being increased due to the incorporation of fasteners. At the same time, alternative mechanical joining methodologies involve complex and costly processing, hindering their industrial application. This work presents a new, simple, cost-efficient and non-weight penalizing mechanical joining technology between a metal sheet and fibre reinforced polymer prepregs consisting of a single-step punching process. In this process, the metallic sheet is completely perforated, while the prepreg is not. The punch pushes the carbon fibres through the metallic hole, with no, or minimal fibre breakage, generating a mechanical interlock. The shear strength and the absorbed energy of the co-cured joint increase with the incorporation of the mechanical interlocking joint.
Analysis of process limits for partial hot stamping with controlled pre-cooling by radiation exchange
Authors: Reihani A , Donat L , Heibel S , Schweiker T , Gienger M , Güner A , Winderlich M , Merklein M
Published: June 2023

The increasing demands on part complexity and tailored properties in form of local strength and ductility cannot be achieved with conventionally manufactured hot stamped body components. To meet the requirements of safety-relevant body parts, partial hot stamping is increasingly used in the automotive industry. One approach to achieve tailored properties on hot stamped parts is based on controlled cooling of the blank prior to forming and quenching. The related furnace technology is based on a furnace chamber in which a cooled aluminum mask protects local areas of the blank from thermal radiation while simultaneously absorbing the blank’s own emitted radiation. The sheet thickness and utilized material significantly influence the controlled radiation exchange and present potential process limits. To analyse these lower process limits, blanks made of the materials 22MnB5 AS150 and 8MnB7 AS150 are partially pre-cooled and hot stamped with different sheet thicknesses. In addition, the process is simulated with AutoForm®R10 and validated by the obtained experimental results. The results show that the sheet thickness is a key influencing factor in the process and significantly affects the mechanical properties after partial hot stamping. Especially sheet thicknesses t0 of 2.25 mm can limit the process, as the effectiveness of the radiation exchange for controlled pre-cooling and phase transformation decreases.
Oxygen-free resistance heating with nitrogen and silane as an energy-efficient heating process for hot stamping
Authors: Behrens B-A , Hübner S , Holländer U , Langohr A , Albracht L , Faramand E , Wehmeyer J , Yarcu S , Raumel S , Wurz M C
Published: June 2023

Hot stamping is a process for the production of ultra-high-strength components used in the automotive industry for passenger protection. In this process, cut blanks are heated in a roller hearth furnace, which is operated with gas, to approx. 950 °C in 8 to 10 min and then formed and quenched in a water-cooled tool. This extends the yield strength of the components up to 1500 MPa. The long heating time is caused by the coating of aluminium and silicon (AlSi) with a thickness of 70 μm. During the 8 to 10 min, an intermetallic phase forms and ensures that the blank does not scale. Due to the long heating time and the energy carrier gas, the process is very energy inefficient and can only be controlled slowly. Resistance heating provides an energy-efficient alternative. Due to the direct current flow through the sheet, up to 68% of the energy can be saved compared to roller hearth furnace heating. The process is a high-speed heating process that can heat sheets to 950 °C in less than 10 seconds. The heating time is not sufficient for conventional coatings to bond sufficiently with the base material, which means that there are currently no suitable coatings for resistance rapid heating. A new approach is to suppress scale formation by reducing the oxygen during heating. By lowering the oxygen partial pressure to the XHV level, scale formation is not possible. At the same time, this absence of oxygen is an ideal condition for applying coatings. Due to the developed resistance heating device, sheets can be heated within a very short time without scale and without the need for fossil fuels.
Study of Microstructural Evolution of Press Hardening Steels using Dilatometer and In-situ Studies for a Simulated Hot Stamping Condition
Authors: Zhu Hong , Yin Hongbin , Sadagopan Sriram
Published: June 2023

Press hardening grades are widely used in automotive industries for safety-critical structural parts due to their unique combination of high strength, excellent formability, and crash performance. Considering various scenarios on thermo-mechanical profiles in different hot stamping lines, achieving the targeted strength and ductility / fracture strain in the hot-stamped parts is still challenging to some hot stampers for some grades. In this investigation, a dilatometer study for Usibor®1500 and two emerging grades Usibor®2000 and Ductibor®1000 under a given hot stamping condition was conducted with consideration of the entire hot-stamping processes (i.e., austenitization, blank transfer, forming and final quenching from 700°C) to understand the differences in critical cooling rates, and evolution of microstructures. Influence of large forming strain (15%) on final properties is also examined for Ductibor®1000 and Ductibor®500 by DIL 805 A/D dilatometer under tensile deformation mode. In-situ observation of microstructural evolution during hot stamping process for Usibor®1500 is explored using Confocal scanning laser microscope to uncover some physical phenomena for further refinement of hot stamping practices.
Development of rapid die cooling technology using the Groove Pressing method in hot stamping process
Authors: Park J M , Park K J , Kong J Y , Yoon S C , Rhee J H , Hyun J S
Published: June 2023

The demand for hot stamping parts in the automobile industry is increasing due to the growth of eco-friendly vehicles with improved crash safety performance and lighter weight. However, the use of ultra-high-strength steel in cold stamping is challenging due to its high yield strength and low elongation. Hot stamping is a widely used process to overcome this challenge, but the long die quenching time reduces its productivity. In order to address this issue, a Groove Pressing method was applied to the sidewall of the die to improve cooling performance without requiring additional devices within the die. The study investigated the required contact pressure between the sheet and the die for the implementation of the groove shape on the sidewall. Computational analysis was performed to design optimal groove shape for the sidewall, and the results showed that Case 3 was the most suitable in terms of cooling performance and contact pressure. The groove shape was incorporated into the die making, and experiments were conducted on aluminized coated 22MnB5 1.2 mm sheet. The results showed that the implementation of the groove shape on the sidewall improved cooling performance, dimensional quality, and mechanical properties without affecting the corrosion resistance of the component. The study demonstrates the potential of the Groove Pressing method as a practical solution for improving the productivity of the hot stamping process in the automobile industry.
Industrial Internet of Things and Big Data Techniques for the Smart Press Shop 4.0 Development in Automotive Industry
Authors: Peinado-Asensi Ivan , Montés N , García E
Published: June 2023

In recent years, one of the main challenges in industry has been to obtain work parameters in real time for later analysis to understand the process better. The purpose is to obtain substantial information about the process for better decision-making and to find out what happens during manufacturing to know both the state of the equipment and the product, looking for savings in maintenance costs and quality controls among others. This has not been an exception for the automotive industry. These challenges have been associated with the concept of Industry 4.0, specifically with Big Data and IIoT (Industrial Internet of Things) techniques. Following this concept, many of the companies and research teams develop their algorithms and ideas based on the installation of new sensors without taking into account the implications that this proposal has in real factories. The cost of the sensor, the installation setup, maintenance, machine modifications and replication for hundreds of machines make many of the ideas fail when innovation is implemented in the companies. For that reason, in our previous work we have introduced a novel concept in Industry 4.0, the development of algorithms by using exclusively the information that is available in the equipment. Machines, as well as presses and general automated systems, include sensors for their automated normal production. These sensors are installed and the information they provide is almost free. Following this philosophy, the present paper proposes the Criterion-360 for real press shops. With this criterion, it is possible to measure a lot of variables with no cost, not only the tonnage, but also, many variables such as the press speed, Counterbalance and overload pressure, Cushion Pressure & Position, lubrication, etc., and therefore with this amount of information many possibilities arise. As the new developed system does not need new sensors and additional installation setup, it is easy and cheap to replicate it in other presses and plants.

This article presents two tools that have been developed from the information obtained with this criterion, these tools are currently in operation and have been used to modify work processes and get the press to work in optimal conditions.
Process Monitoring using Digital Twin-Based Sensors integrated in Tool Clamping Surfaces
Authors: Kurth Robin , Alaluss Mohaned , Wagner Martin , Tehel Robert , Riemer Matthias , Ihlenfeldt Steffen
Published: June 2023

Process monitoring in forming technology can serve as a basis for transparent manufacturing and closed-loop control systems. Particularly, sensor systems associated with tool clamping interfaces offer great potential for robust inline process monitoring but are hardly investigated. In this paper, a concept to monitor a sheet metal forming process combined with a digital twin-based approach for virtual sensors is introduced. Here, sensors integrated into the T-slots of tool clamping surfaces in forming machines are enhanced by a mathematical representation of the elasto-mechanical behavior of the tool clamping interfaces. Moreover, the potential of the certain sensor system for inline process monitoring is highlighted. The resulting approach is substantiated by simulative analysis and by experimental investigation.
Effect of pre-strain on edge formability of high strength steels for chassis applications
Authors: Payà A , Lara A , Frómeta D , Marés M , Gil I , Arenillas C
Published: June 2023

There is a high level of uncertainty in the prediction of edge cracking during the design and manufacturing of high strength sheet metal products. Edge ductility is a complex parameter to measure since it is not an intrinsic property of the material, but it also depends on the trimming strategy/parameters that have been applied to the edge (edge preparation method, cutting/punching clearance, etc.). Furthermore, most forming processes involve more than one operation where the material can be deformed in a first stage, then trimmed or punched and further deformed in a final forming step to obtain the desired shape. Therefore, in order to design a robust and safe forming process able to predict the risk of edge cracking, it is crucial to understand the influence of pre-strain on the residual formability of trimmed edges. This paper analyses the effect of different pre-strain levels and paths (uniaxial tension, plane strain and equi-biaxial stretching) on the sheared edge ductility of a Complex Phase (CP) steel and a high strength low alloy (HSLA) steel used for automobile chassis applications. To this purpose, rectangular specimens are cut out from pre-strained samples and punched. Hole Tension Tests (HTTs) in combination with Digital Image Correlation (DIC) are carried out to determine the edge fracture strain of undeformed and pre-strained samples. The results are discussed in terms of major strains obtained from DIC. The proposed methodology allows describing the edge cracking sensitivity of high-strength steel sheets as a function of the pre-deformation state and can be useful to predict the risk of edge cracking more accurately in forming simulations.
Hot-forming of a 980 MPa third generation advanced high strength steel
Authors: Midawi Abdelbaset R H , Tolton C , George R , Subramanian M , Skszek T , Butcher C , Worswick M
Published: June 2023

This paper considers the effect of processing route on the final microstructure hardness and tensile behavior of a 980 MPa third generation advanced high strength steel (3G-AHSS). Of particular interest is the use of a hot stamping thermal schedule that mimics a quench and partition (Q&P) heat treatment process normally used to produce Q&P grade steel sheet. For comparison purposes, samples were also produced using a quench and temper (Q&T) processing history. The experiments were performed using a Gleeble 3500 thermo-mechanical simulator system. Large coupons were produced using both processing routes from which microstructure, hardness, and tensile samples were extracted. Mechanical properties results were compared with the as-received material. Both processing routes resulted in strength levels that were close to that of the as-received material; however, the total elongation of the Q&P processed samples was 52% higher than that of the Q&T processed material.
Crashworthiness evaluation of press hardened steels with different lath-like microstructures.
Authors: Aroca V P , Philippot C , Pujante J , Frómeta D , Caballero F G , Capdevila C
Published: June 2023

The deployment of Press Hardened Steels (PHSs) in the Body-In-White structures that took place during the two last decades is at the origin of a breakthrough weight saving on vehicles while guaranteeing the safety requirements of the automotive industry. The production of parts with complex shapes and a high strength between 1500-2000MPa was made possible by taking advantage of the hot rheology of austenite combined with the fast cooling obtained by in-die quenching leading to auto-tempered martensitic microstructures. In the present work, PHS1500 was hot stamped with different thermomechanical processes to promote different lath-like microstructures (bainite, tempered martensite…). An innovative approach is proposed to link the complex microstructures formed between thermoregulated dies to the mechanical behaviour and local ductility of these materials during crash-like solicitations. The microstructure has been characterised through a multi-characterization technique approach including light optical microscopy, scanning electron microscopy and X-ray diffraction. The local ductility is assessed with a combination of crack initiation tests (bending, notch tensile test) and crack propagation resistance tests (Essential work of fracture). Despite similar microstructural crystallographic features, lower bainite and auto-tempered martensite can lead to very different strength – local ductility compromise.
Research on toolpath optimization of robot-assisted incremental flanging
Authors: Cheng X , Zhao Y X , Yu Z Q , Chen W
Published: June 2023

Robot-assisted incremental flanging (RAIF), a cost-effective and promising forming technology for producing large-size open-edge flanged parts in multi-variety and small batches, is expected to be widely used in aerospace, automotive and other technological industries. As a multi-pass incremental forming technique, the forming quality of the flanged parts is dependent on the movement of the roller controlled by the robot directly. The toolpath of a certain pass is determined by the rotation velocity (to adjust the flanging angle), the revolution velocity (to complete the flanging process of the whole blank sheet) and the matching relationship between two velocities (synchronously or asynchronously). In this paper, the process principle of RAIF technology is illustrated by using the example of shrink flanging firstly, then the effects of asynchronous motion and synchronous motion on the forming quality of a 60° flanged part made of the 5A06 aluminum alloy are compared while the rotation and revolution velocity of the roller are set to 1°/s and 1.8°/s, respectively. Results show that the forming quality is improved significantly that the maximum height of edge waves is decreased from 2.1 mm to 0.19 mm when the roller is set to rotate and revolve synchronously. Based on the above comparison results, the rotation velocity is set as 1°/s, 1.33°/s, 2°/s and 4°/s respectively to further investigate the effect of different toolpaths on the forming quality under synchronous motion conditions. It can be found that the maximum stress gradually increases from 575.4 MPa to 621.6 MPa when the rotation velocity decreases from 4°/s to 1°/s.
Evaluation of hardening laws coupled with shear modified Lemaitre damage model for fracture prediction in incremental sheet forming
Authors: Kumar Abhishek , Narasimhan K
Published: June 2023

Incremental sheet forming (ISF) is an emerging technology for manufacturing sheet metal components with fewer tools and equipment compared to conventional sheet forming. In this process, forming is generally performed without dies and punches and a simple hemispherical shaped tool can be used for shaping the final component. Forming limit in incremental sheet forming can be defined by the maximum formable wall angle. Finite element analysis can be used for fracture prediction by using a damage model. Also, to define the material flow behaviour hardening law should be incorporated into the finite element model. In this study four different hardening laws were used with shear modified Lemaitre damage model for fracture prediction during ISF of AA1050 alloy. The effectiveness of Hollomon, Johnson-Cook, Ludwigson and Swift hardening laws were compared for fracture prediction. Further, the predicted fracture wall angles were compared with the experimental observations. The results were analysed in terms of damage and strain evolution for the predicted fracture wall angles based on different hardening models.
The effect of scrap originating trace elements on the properties of low alloyed steels
Authors: Ahmed Shahroz , Sabr Ali , Peltola Ari , Oja Olli , Järn Sanna , Kaijalainen Antti , Penney David , Peura Pasi
Published: June 2023

The present intention to reach fossil-free steel manufacturing will inevitably result in an increase in the use of steel scrap as a raw material for steel production. Consequently, the amounts of elements, seen as impurities, will increase in steels. This has already been seen in electric arc furnace (EAF) processed steels, where the Cu and Sn levels have doubled in some cases after 1980’s. This may cause problems, as it is well-known, that some impurity elements have harmful effects on the properties of steel. This has been widely studied in low-alloy steels containing chromium and molybdenum which are widely used in components for the petroleum and electrical power generation applications. However, limited number of studies have been performed on formable steel grades, and the published reports/articles have mostly concentrated on the effects of P and B. Thus, there is still a need to understand the roles of other impurity elements. In the present study, a formable C-Mn steels containing additions (either individually or in combination) of Cu and Sn is investigated. The samples were cold rolled and annealed following typical time-temperature profiles of modern continuous annealing lines. Mechanical and forming properties (incl. bending and cupping tests) are determined as well as elemental profile analysis is conducted. The results identify that minor additions of impurity elements, in this case Cu and Sn, does not affect the mechanical and forming properties of low alloyed formable steel grades considerably.