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1 – 10 of 493Changyang Li, Huapeng Wu, Harri Eskelinen and Haibiao Ji
This paper aims to present a detailed mechanical design of a seven-degrees-of-freedom mobile parallel robot for the tungsten inert gas (TIG) welding and machining processes in…
Abstract
Purpose
This paper aims to present a detailed mechanical design of a seven-degrees-of-freedom mobile parallel robot for the tungsten inert gas (TIG) welding and machining processes in fusion reactor. Detailed mechanical design of the robot is presented and both the kinematic and dynamic behaviors are studied.
Design/methodology/approach
First, the model of the mobile parallel robot was created in computer-aided design (CAD) software, then the simulation and optimization of the robot were completed to meet the design requirements. Then the robot was manufactured and assembled. Finally, the machining and tungsten inert gas (TIG) welding tests were performed for validation.
Findings
Currently, the implementation of the robot system has been successfully carried out in the laboratory. The excellent performance has indicated that the robot’s mechanical and software designs are suitable for the given tasks. The quality and accuracy of welding and machining has reached the requirements.
Originality/value
This mobile parallel industrial robot is particularly used in fusion reactor. Furthermore, the structure of the mobile parallel robot can be optimized for different applications.
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Elisa Verna, Gianfranco Genta and Maurizio Galetto
The purpose of this paper is to investigate and quantify the impact of product complexity, including architectural complexity, on operator learning, productivity and quality…
Abstract
Purpose
The purpose of this paper is to investigate and quantify the impact of product complexity, including architectural complexity, on operator learning, productivity and quality performance in both assembly and disassembly operations. This topic has not been extensively investigated in previous research.
Design/methodology/approach
An extensive experimental campaign involving 84 operators was conducted to repeatedly assemble and disassemble six different products of varying complexity to construct productivity and quality learning curves. Data from the experiment were analysed using statistical methods.
Findings
The human learning factor of productivity increases superlinearly with the increasing architectural complexity of products, i.e. from centralised to distributed architectures, both in assembly and disassembly, regardless of the level of overall product complexity. On the other hand, the human learning factor of quality performance decreases superlinearly as the architectural complexity of products increases. The intrinsic characteristics of product architecture are the reasons for this difference in learning factor.
Practical implications
The results of the study suggest that considering product complexity, particularly architectural complexity, in the design and planning of manufacturing processes can optimise operator learning, productivity and quality performance, and inform decisions about improving manufacturing operations.
Originality/value
While previous research has focussed on the effects of complexity on process time and defect generation, this study is amongst the first to investigate and quantify the effects of product complexity, including architectural complexity, on operator learning using an extensive experimental campaign.
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Milad Shabanian and Nicole Leo Braxtan
Thermomechanical behavior of intermediate-size beam-to-wall assemblies including Glulam-beams connected to cross-laminated timber (CLT) walls with T-shape steel doweled…
Abstract
Purpose
Thermomechanical behavior of intermediate-size beam-to-wall assemblies including Glulam-beams connected to cross-laminated timber (CLT) walls with T-shape steel doweled connections was investigated at ambient temperature (AT) and after and during non-standard fire exposure.
Design/methodology/approach
Three AT tests were conducted to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Two post-fire performance (PFP) tests were performed to study the impact of 30-min (PFP30) and 60-min (PFP60) partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were exposed to fire in a custom-designed frame, then cooled and loaded to failure. A fire performance (FP) test was conducted to study the fire resistance (FR) during non-standard fire exposure by simultaneously applying fire and a mechanical load equal to 65% of the AT load carrying capacity.
Findings
At AT, embedment failure of the dowels followed by splitting failure at the Glulam-beam and tensile failure of the epoxy between the layers of CLT-walls were the dominant failure modes. In both PFP tests, the plastic bending of the dowels was the only observed failure mode. The residual strength of the assembly was reduced 14% after 30 min and 37% after 60 min of fire exposure. During the FP test, embedment failure of timber in contact with the dowels was the only major failure mode, with the maximum rate of displacement at 51 min into the fire exposure.
Originality/value
This is the first time that the thermomechanical performance of such an assembly with a full-contact connection is presented.
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Milad Shabanian and Nicole Leo Braxtan
3-ply cross-laminated timber (CLT) is used to investigate the thermo-mechanical performance of intermediate-size assemblies comprised of T-shaped welded slotted-in steel doweled…
Abstract
Purpose
3-ply cross-laminated timber (CLT) is used to investigate the thermo-mechanical performance of intermediate-size assemblies comprised of T-shaped welded slotted-in steel doweled connections and CLT beams at ambient temperature (AT), after and during non-standard fire exposure.
Design/methodology/approach
The first set of experiments was performed as a benchmark to find the load-carrying capacity of the assembly and investigate the failure modes at AT. The post-fire performance (PFP) test was performed to investigate the residual strength of the assembly after 30-min exposure to a non-standard fire. The fire-performance (FP) test was conducted to investigate the thermo-mechanical behavior of the loaded assembly during non-standard fire exposure. In this case, the assembly was loaded to 67% of AT load-carrying capacity and partially exposed to a non-standard fire for 75 min.
Findings
Embedment failure and plastic deformation of the dowels in the beam were the dominant failure modes at AT. The load-carrying capacity of the assembly was reduced to 45% of the ambient capacity after 30 min of fire exposure. Plastic bending of the dowels was the principal failure mode, with row shear in the mid-layer of the CLT beam and tear-out failure of the header sides also observed. During the FP test, ductile embedment failure of the timber in contact with the dowels was the major failure mode at elevated temperature.
Originality/value
This paper presents for the first time the thermo-mechanical performance of CLT beam-to-girder connections at three different thermal conditions. For this purpose, the outside layers of the CLT beams were aligned horizontally.
Highlights
Load-carrying capacity and failure modes of CLT beam-to-girder assembly with T-shaped steel doweled connections at ambient temperature presented.
Residual strength and failure modes of the assembly after 30-min partially exposure to the non-standard fire provided throughout the post-fire performance test.
Fire resistance of the assembly partially exposed to the non-standard fire highlighted.
Load-carrying capacity and failure modes of CLT beam-to-girder assembly with T-shaped steel doweled connections at ambient temperature presented.
Residual strength and failure modes of the assembly after 30-min partially exposure to the non-standard fire provided throughout the post-fire performance test.
Fire resistance of the assembly partially exposed to the non-standard fire highlighted.
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Peter Burggraef, Johannes Wagner, Matthias Dannapfel and Sebastian Patrick Vierschilling
The purpose of this paper is to investigate the benefit of pre-emptive disruption management measures for assembly systems towards the target dimension adherence to delivery times.
Abstract
Purpose
The purpose of this paper is to investigate the benefit of pre-emptive disruption management measures for assembly systems towards the target dimension adherence to delivery times.
Design/methodology/approach
The research was conducted by creating simulation models for typical assembly systems and measuring its varying throughput times due to changes in their disruption profiles. Due to the variability of assembly systems, key influence factors were investigated and used as a foundation for the simulation setup. Additionally, a disruption profile for each simulated process was developed, using the established disruption categories material, information and capacity. The categories are described by statistical distributions, defining the interval between the disruptions and the disruption duration. By a statistical experiment plan, the effect of a reduced disruption potential onto the throughput time was investigated.
Findings
Pre-emptive disruption management is beneficial, but its benefit depends on the operated assembly system and its organisation form, such as line or group assembly. Measures have on average a higher beneficial impact on group assemblies than on line assemblies. Furthermore, it was proven that the benefit, in form of better adherence to delivery times, per reduced disruption potential has a declining character and approximates a distinct maximum.
Originality/value
Characterising the benefit of pre-emptive disruption management measures enables managers to use this concept in their daily production to minimise overall costs. Despite the hardly predictable influence of pre-emptive disruption measures, these research results can be implemented into a heuristic for efficiently choosing these measures.
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