Assembly Work Research Articles

Experimental investigation on seismic behaviors of precast concrete shear walls with sleeve grouting defects

The grouted sleeve connector is one of the most widely used connections in precast concrete shear wall structures. Due to the technology limit of the assembly workers, the sleeve grouting often has defects, which could significantly weaken their practical performance. Only considering the effect of defects on the bearing capacity of the sleeve connector cannot simulate the effect of defects in actual engineering. To this end, an experiment was carried out to investigate the seismic performance of precast concrete shear walls with sleeve grouting defects. Four full-scale precast concrete shear walls with different defect levels of insufficient grouting were designed and tested under cyclic loads. The development of concrete cracking, failure mode, hysteresis features, load-bearing capacity, stiffness degradation, structural ductility and energy-dissipation capacity are analyzed to reveal the influence of the sleeve grouting defects on precast concrete shear walls. The test results indicated that with the increase of the defect level, the opening gap between the bottom of the wall and the top of the foundation beam widened, and the failure mode changed from tensile fracture of reinforcing steel bar to anchorage failure of the tensile reinforcement on the defective side. Meanwhile, as the level of grouting defects increased, the bearing capacity decreased, and the specimen failed prematurely. The effect of the grouting defects on cracking load was minor, while they had a significant influence on the yield bearing capacity, peak bearing capacity and ultimate bearing capacity. The experimental results also indicated that the grouting defects caused the weakening of the stiffness, ductility and energy dissipation of the precast concrete shear walls. The presented work could be used for defect prevention and evaluation of precast concrete shear walls with sleeve grouting defects.

New test equipment for testing the watertightness of facade structures in-situ

With the current trend of construction of high-rise buildings in urban agglomerations, ensuring watertightness of their facade structures exposed to the effects of high-intensity wind-driven rain is coming to the fore. Laboratory experimental testing of water impermeability of elements of building envelope structures and their joints is performed in the process of preparation of the facade implementation in accordance with STN EN 1027: 2002 in rain chamber equipment. Due to the fact that the quality and functional properties of the finished facade are significantly influenced by the assembly technology and work discipline in its implementation, successful testing of the facade and its components in the rain chamber may not guarantee the watertightness of the finished facade. For this reason, the investor has the opportunity to check the finished facade in terms of its hydrodynamic safety and reliability by a functional test of its watertightness according to the standard regulation STN EN 13051 Curtain walling - Watertightness - Site test. The article describes in detail the new technological device for the implementation of the in-situ watertightness test of the facade, the measurement methodology, including its functional verification on the facade of the high-rise administrative building Nivy Tower in Bratislava.

What consumers think about product self-assembly: Insights from big data

As e-commerce expands rapidly from small inexpensive products to major ones, more sellers design and deliver their products as unassembled, compact kits to make logistics more efficient and cost effective. While sensible from an operation’s perspective, this practice inadvertently shifts often significant amounts of assembly work to consumers. Drawing on the literatures of product co-creation and consumer satisfaction, this study investigates various effects of this practice on buyers. Results, obtained from the analysis of consumers’ online reviews, show that the ease of assembly is a significant determinant of satisfaction with and recommendation of products. Results also indicate that, as an experience product attribute that cannot be assessed pre-purchase, assembly work is a major source of consumer concern and discontent. On the other hand, findings show a positive relationship between the volume (but not the complexity) of consumer assembly work and their sense of value for money from their purchase.

THEORETICAL AND PROBABILISTIC CALCULATION OF THE NUMBER OF THIN EQUAL COMPENSATORS WHEN ACHIEVING ASSEMBLY ACCURACY BY THE REGULATION METHOD

The article discusses a method for calculating the dimensions of thin expansion joints of the same length (spacers) used to achieve the accuracy of the closing links of linear assembly dimensional chains of machines by the control method. The technique makes it possible to reasonably determine the number and accuracy parameters of compensators in a set for one product and reduce the proportion of defective products by taking into account possible errors in assembly equipment and assembly work. The technique can be useful for engineers developing technical processes for assembling machines.

Analysis of Measurement and Calculation of MSD Complaint of Chassis Assembly Workers Using OWAS, RULA and REBA Method

Car assembly is a combination of all components that form one completed vehicle unit. The work process is manually done and repeatedly, which contributes to a risk of musculoskeletal disorders (MSD). Chassis assembly is a job with a high level of complexity and associated with MSD risk for its employees. This study consists of 30 assembly activities divided into six groups based on posture and working methods used during the work process. Group A consists of 7 assemblies, Group B consists of 8 assemblies, Group C consists of 5 assemblies, Group D consists of 2 assemblies, Group E consists of 5 assemblies, and Group F consists of 3 assemblies. This study aims to compare the measurement and calculation of the risk level of MSD workers by using the RULA, REBA, and OWAS methods. The results of the measurements and computations acquired using these three approaches yielded the same risk category: 83.33 % medium risk/dangerous in working groups A, C, D, E, and F, and 16.67 % very high risk/highly hazardous in working group B. These six groups, particularly group B, requires immediate attention to reduce worker complaints of MSD.

Derived patterns of musculoskeletal symptoms and their relationships with ergonomic factors among electronic assembly workers: A latent class analysis

Introduction: Multi-site musculoskeletal symptoms (MSS) are considered to be more common and have more serious consequences than single-site MSS. This study aimed to determine whether derived patterns of MSS may be identified in electronic assembly workers and if extracted MSS classes are associated with personal and work-related factors. Method: A cross-sectional questionnaire study was performed with 700 participating electronic assembly workers. The questionnaire included individual factors, psychosocial and physical exposures, and MSS. The derived patterns of MSS and their relationships with ergonomic factors were analyzed using latent class analysis (LCA) and multinomial logistic regression models (MLRM). Results: The 1-year prevalence of MSS affecting only one body site or two or more body sites was 14.9% and 32.7%, respectively. The results of LCA showed three distinct classes of MSS patterns, which were labelled ‘MSS in most sites’ (5.0%), ‘MSS in neck and shoulder’ (27.0%), and ‘MSS in one or no site’ (68.0%). The results of MLRM showed that the ‘MSS in neck and shoulder’ was associated with job tenure (OR 5.579, 95% CI 2.488–12.511), excessive dynamic and static loads (OR 3.868, 95% CI 1.702–8.793 and OR 5.270, 95% CI 2.020–13.747, respectively); while the ‘MSS in most sites’ was associated with high job demands (OR 4.528, 95% CI 1.647–12.445) and excessive dynamic loads (OR 111.554, 95% CI 4.996–2490.793). Conclusions: The results showed unique patterns of MSS among electronic assembly workers that were associated with personal and work-related factors. Practical applications: The findings highlight that the high prevalence of multi-site MSS in this group should be a focus. It also provides further evidence that LCA considering the number and location of anatomical sites involving MSS can be used to determine distinct classes of MSS patterns, which is of great significance for the epidemiological study and management of MSS in the future.

Wire Harness Assembly Process Supported by Collaborative Robots: Literature Review and Call for R&D

The wire harness assembly process is a complicated manufacturing activity, which is becoming more complex because of the evolving nature of mechatronic and electronic products that require more connectors, sensors, controllers, communication networking, etc. Furthermore, the demand for wire harnesses continues to grow in all industries worldwide as the majority of equipment, appliances, machinery, vehicles, etc., are becoming “smart” (i.e., more mechatronic or electronic). Moreover, most of the wire harness assembly process tasks are done manually, and most of these are considered non-ergonomic for human assembly workers. Hence, the wire harness manufacturing industry is faced with the challenge of increasing productivity while improving the occupational health of its human assembly workers. The purpose of this paper is to conduct a literature review exploring the state of the use of collaborative robots in the wire harness assembly process due to their potential to reduce current occupational health problems for human assembly workers and increase the throughput of wire harness assembly lines, and to provide main findings, discussion, and further research directions for collaborative robotics in this application domain. Eleven papers were found in the scientific literature. All papers demonstrated the potential of collaborative robots to improve the productivity of wire harness assembly lines, and two of these in particular on the ergonomics of the wire harness assembly process. None of the papers reviewed presented a cost–benefit or a cycle time analysis to qualitatively and/or quantitatively measure the impact of the incorporation of collaborative robots in the wire harness assembly process. This represents an important area of opportunity for research with relevance to industry. Three papers remark on the importance of the integration of computer vision systems into a collaborative wire harness assembly process to make this more versatile as many types of wire harnesses exist. The literature review findings call for further research and technological developments in support of the wire harness manufacturing industry and its workers in four main categories: (i) Collaborative Robotics and Grippers, (ii) Ergonomics, (iii) Computer Vision Systems, and (iv) Implementation Methodologies.

Mixed-model sequencing versus car sequencing: comparison of feasible solution spaces

ABSTRACT In the automotive industry, a great challenge of production scheduling is to sequence cars on assembly lines. Among a wide variety of scheduling approaches, academics and manufacturers pay close attention to two specific models: Mixed-Model Sequencing (MMS) and Car Sequencing (CS). Whereas MMS explicitly considers the assembly line balance, CS operates with sequencing rules to find the best car sequence fulfilling the assembly plant requirements, like minimising work overload for assembly workers. Meanwhile, automakers including Renault Group are increasingly willing to consider other requirements, like end-to-end supply chain matters, in production planning and scheduling. In this context, this study compares MMS- and CS-feasible solution spaces to determine which workload-oriented sequencing model would be the most appropriate to later integrate new optimisation. We introduce two exact methods based on Dynamic Programming to assess the gap between both models. Numerical experiments are carried out on real-life manufacturing features from a Renault Group assembly plant. They show that MMS generates more feasible sequences than CS regardless of the sequencing rule calculation method. Only the sequencing rules used by real-life production schedulers result in a higher number of distinct feasible sequences for CS, highlighting that the plant might select a sequence with work overload situations.

Study on ergonomic intervention to relieve work-related musculoskeletal disorders among assembly workers in a railway vehicle manufacturing enterprise

Study on ergonomic intervention to relieve work-related musculoskeletal disorders among assembly workers in a railway vehicle manufacturing enterprise

Influencing factors for work-related musculoskeletal disorders among assembly workers in four manufacturing enterprises

Influencing factors for work-related musculoskeletal disorders among assembly workers in four manufacturing enterprises

Projectifying feminism: exploring the conditions for feminist politics in international development aid

As an organisational form, the project poses a challenge today for the possibility of articulating feminist politics, understood as feminist visions and ambitions. With a focus on women’s organisations working in international development aid, we examine how the project format and its managerial attributes shape the possibility of articulating feminist politics. Mobilising assemblage thinking on a material consisting mainly of interviews with project workers in women’s organisations, we show that these organisations engage in assembly work to fit their activism with the project format, such as translating feminist ambitions into bureaucratic procedures and notions of temporality, activating repertoires of expertise, and adopting marketised approaches to development. We conclude that the project format depoliticises feminist politics, although it does not make the articulation of feminist ambitions impossible. Assemblage thinking is suggested as a suitable framework for feminist research when investigating how contemporary governing arrangements influence the articulation of feminist politics.

CALCULATION OF FIXED COMPENSATORS OF DIFFERENT LENGTHS TAKING INTO ACCOUNT THE ACCURACY OF ASSEMBLY WORKS

CALCULATION OF FIXED COMPENSATORS OF DIFFERENT LENGTHS TAKING INTO ACCOUNT THE ACCURACY OF ASSEMBLY WORKS

Parameters of effects in decision making of automotive assembly line using the Analytical Hierarchy Process method

The automotive industry contributes high income to most of the countries. The assembly line is an essential part of the automotive industry because it combines all the components into a complete body unit. Assembly lines often experience delays in meeting production targets, requiring overtime to complete. Musculoskeletal Disorder (MSD) complaints among assembly workers predominantly lie in trimming, chassis, and finishing processes. Improvements are needed to reduce complaints according to the priority process. This study aims to prioritize the process on the assembly line with the parameters of work position, workload, work layout and equipment. This study implements the Analytical Hierarchy Process (AHP) method to achieve the objectives of the decision-making process. Preliminary weighting priorities for chassis, finishing and trimming are 0.6153, 0.2313 and 0.1533; respectively highest weight is in the chassis process and will be a priority for this study in optimizing solutions.

Efficiency forecasting of electric bundle assembly with use of ANN model

Management of production systems requires making immediate decisions based on the data generated in bulk by IT systems. In this case, it can be helpful to use models of artificial neural networks (ANN) that, on the grounds of accessible data, will determine results of the made decision. One of the key problems in production companies is determination of execution time and cost of a production order. The problem is especially important in a company manufacturing a variable product line with a big part of manual operations. In the article, the way of building an ANN model for efficiency forecasting of the assembly process of electric bundles is presented. With regard to the very wide and variable product line, the products with different complexity degree are manufactured on three types of assembly lines. The assembly processes are performed on the assembly lines manually by groups of workers, so efficiency of the process is influenced mostly by skills and experience of these workers. Therefore, numbers of new assembly workers assigned to individual assembly lines and quantities of new products in the production schedule are selected as explanatory variables in the ANN model. The explained variable in the ANN model is production volume of the manufactured electric bundles.

Static Bearing Capacity Investigation of a Novel Prefabricated Light-Steel Beam–Column Connection

In this study, a novel prefabricated light-steel beam–column connection consisting of a thin-walled rectangular hollow section column and two cold-formed steel truss beams is proposed and investigated by carrying out experimental tests. Eight cruciform beam–column connection specimens with different configurations are fabricated and tested to failure under monotonic static loading. First, failure mode and the loading–displacement curve of each specimen are investigated. Consequently, the effect of three variables, including truss-beam configuration, truss-beam type, and with or without sleeve tube reinforcing the column, on the static bearing capacity of the proposed connection and the deflection of the truss beams are investigated. It is found that plug welding the sleeve to the column can significantly increase the static bearing capacity of the proposed connection. In addition, fillet welding connecting the column and the channel connectors to accommodate the end of the truss beams is crucial to the static bearing capacity of the proposed beam–column connection. Because beam–column connections with single-truss beams have a higher load-bearing capacity and require less material and assembly work, it is recommended to adopt this type of configuration for the proposed connection.

Reaction force exposure for tightening tool users: A psychophysical based experimental study of electric right-angle nutrunners

Reaction forces from nutrunner tools constitute a risk of developing MSDs. However, recommendations for sustainable reaction force levels are lacking. The aim of this study was to inform recommendations regarding reaction load exposures from right-angle nutrunners. Through a psychophysics approach, experienced assembly workers subjectively assessed reaction loads when using a nutrunner in six combinations of tool tightening strategy, work-pace and screw-joint stiffness. Electromyography, tool and joint parameters were measured. Regardless of tightening strategy, joint stiffness and work-pace combinations, no large differences in acceptable tightening torque, peak reaction force, and handle displacement were observed. However, acceptable jerk and impulse differed substantially between the TurboTight® (high-acceleration) and QuickStep® (conventional) tightening strategies. Although the TurboTight® strategy overall showed reduced peak muscular activities compared to the QuickStep®, the participant-rated acceptable torque levels were similar, plausibly due to TurboTights’ high jerk levels. Jerk and impulse are hypothesized to influence the perception of reaction loads.

Danger, high voltage! Using EEG and EOG measurements for cognitive overload detection in a simulated industrial context

Industrial settings will be characterized by far-reaching production automation brought about by advancements in robotics and artificial intelligence. As a consequence, human assembly workers will need to adapt quickly to new and more complex assembly procedures, which are most likely to increase cognitive workload, or potentially induce overload. Measurement and optimization protocols need to be developed in order to be able to monitor workers’ cognitive load. Previous studies have used electroencephalographic (EEG, measuring brain activity) and electrooculographic (EOG, measuring eye movements) signals, using basic computer-based static tasks and without creating an experience of overload. In this study, EEG and EOG data was collected of 46 participants performing an ecologically valid assembly task while inducing three levels of cognitive load (low, high and overload). The lower individual alpha frequency (IAF) was identified as a promising marker for discriminating between different levels of cognitive load and overload.

A chromosome-level genome assembly of Paracymoriza distinctalis (Lepidoptera: Crambidae: Acentropinae).

Paracymoriza distinctalis is a semiaquatic lepidopteran insect, which is of great value for studying the differentiation of the Pyraloidea superfamily. However, the understanding of heredity, evolution, and functional genomics of P. distinctalis are limited by few genome-wide resources. Here, we applied PacBio sequencing and the chromosome capture technique to assemble the first P. distinctalis genome from a single female individual. The genome size is 1.2 Gb with 32 chromosomes and the N50 is 38.91 Mb. Approximately 576.37 Mb, accounting for 48.93% of the genome, was identified as repeats. The genome comprises 39,003 protein-coding genes, 66.56% of which were functionally annotated. Comparative genomics analysis suggested that the common ancestor of P. distinctalis and Chilo suppressalis lived ~83.5 million years ago. This chromosome-level genome assembly work is not only conducive to the understanding of P. distinctalis, but also may promote the study of the genomes of other lepidopteran species.

Addressing gender discrimination in Vietnam's light manufacturing industry: What role for labor law?

This paper explores women workers’ experiences of gender discrimination at work in Vietnam and whether labor law might enable them to challenge discriminatory practices. Interviews with workers reveal how discrimination is generated and entrenched through seemingly neutral workplace rules and culture. The coercive and intensive nature of assembly work has deterred or prevented working mothers from enjoying fair and decent work. Survey findings on female workers’ mobilization of the law suggest that women who have experienced discrimination in the past are less inclined to choose a legal means when faced with future discrimination. In most cases, women would choose not to take any action or opt for a non-legal means to raise their voices. In conclusion, even though women workers in general do not consider law a potential tool to tackle discrimination, they have absorbed and appropriated the language of the law to make sense of unfair practices at work.

Biomechanical investigation of load differences on the upper extremities in dynamic hand strikes and isometric hand pushes during assembly tasks

AbstractThis study determines the effects of increasing forces on different musculoskeletal load parameters, such as muscle activity and joint movement, during assembly task‐related dynamic hand strikes and isometric push forces. Fifteen subjects (12 men and 3 women) were instructed to strike and push on a force plate in two selected conditions. In the first condition, the palmar surface of the dominant hand is oriented horizontal to the measuring surface; in the second condition, the body position is maintained, but the hand is turned 90° to allow the use of the ulnar side of the hand (fist strike position). The subjects accomplished four force levels in ascending order (i.e., 150, 250, 350, and 400 N) within the corresponding striking and pushing conditions. The extracted kinematic variables of interest were strike velocity, recoil velocity, force plate contact time, peak vertical reaction force component (force plate), force impulse, muscle activity, and maximum joint ranges of motion during the push or strike process. Differences in the results between pushes and strikes and, under certain circumstances, between fist and palm strikes were identified. Increasing push forces correlate with the muscle activity in the pectoralis and lower arm extensor muscles. The fact that, at push forces > 250 N, the subjects modify and adapt their upper body and arm posture to achieve the required force could reveal an obvious feasibility limit and explain why assembly workers tend to use their hands as a hammer.