Search Results (19)

This work presents the structural analysis and validation of a sub-250 g FPV drone chassis, emphasizing both theoretical rigor and practical applicability. The novelty of this contribution lies in four complementary aspects. First, the structural philosophy introduces a screwless frame with interchangeable arms, joined through interlocking mechanisms inspired by traditional Japanese joinery. This approach mitigates stress concentrations, reduces weight by eliminating fasteners, and enables rapid arm replacement in the field. Second, validation relies on nonlinear static and transient FEM simulations, explicitly including crash scenarios at 5 m/s, systematically cross-checked with bench tests and instrumented flight trials. Third, unlike most structural studies, the framework integrates firmware (Betaflight), GPS, telemetry, and real flight performance, linking structural reliability with operational robustness. Finally, a practical materials pathway was implemented through a dual-track strategy: PETG for rapid, low-cost prototyping, and carbon fiber composites as the benchmark for production-level performance. Nonlinear transient FEM analyses were carried out using Inventor Nastran under multiple load cases, including maximum motor acceleration, pitch maneuvers, and lateral impact at 40 km/h, and were validated against simplified analytical models. Experimental validation included bench and in-flight trials with integrated telemetry and autonomous features such as Return-to-Home, demonstrating functional robustness. The results show that the prototype flies correctly and that the chassis withstands the loads experienced during flight, including accelerations up to 4.2 G (41.19 m/${\mathrm{s}}^2$), abrupt changes in direction, and high-speed maneuvers reaching approximately 116 km/h. Quantitatively, safety factors of approximately 5.3 under maximum thrust and 1.35 during impact confirm sufficient structural integrity for operational conditions. In comparison with prior works reviewed in this study, the key contribution of this work lies in unifying advanced, crash-resilient FEM simulations with firmware-linked flight validation and a scalable material strategy, establishing a distinctive and comprehensive workflow for the development of sub-250 g UAVs. Full article

Alkyd resins are among the most common coatings used for exterior wood joinery. In Romania, solvent-borne alkyd coatings are widely used to finish wood. The study aims to compare the performance after 7 years of outdoor exposure of two types of alkyd coatings, a semi-transparent brown stain with micronized pigments (Alk1) and an opaque white enamel (Alk2), applied directly on wood or wood pre-treated with three types of resins: acryl-polyurethane (R1), epoxy (R2), and alkyd-polyurethane (R3). Fir (Abies alba) wood served as the substrate. Cracking, coating adhesion, and biological degradation were periodically assessed through visual inspection and microscopy. Additionally, a cross-cut test was performed, and the loss of coating on the directly exposed upper faces was measured using ImageJ. The results indicated that resin pretreatments somewhat reduced cracking but negatively affected coating adhesion after long-term exposure. All samples pretreated with resins and coated with Alk1 lost more than 50% (up to 78%) of the original finishing film by the end of the test. In comparison, coated control samples lost less than 50%. The Alk2 coating exhibited a film loss between 2% and 12%, compared to an average loss of 9% for the coated control. Overall, samples pretreated with alkyd-polyurethane resin (R3) and coated with alkyd enamel (Alk2) demonstrated the best performance in terms of cracking, adhesion, and discoloration. Full article

Robotic timber joinery demands integrated, adaptive methods to compensate for the inherent dimensional variability of wood. We introduce a seamless robotic workflow to enhance the measurement accuracy of the Workpiece Coordinate System (WCS). The approach leverages a Zivid 3D camera mounted in an eye-in-hand configuration on a KUKA industrial robot. The proposed algorithm applies a geometric method that strategically crops the point cloud and fits planes to the workpiece surfaces to define a reference frame, calculate the corresponding transformation between coordinate systems, and measure the cross-section of the workpiece. This enables reliable toolpath generation by dynamically updating WCS and effectively accommodating real-world geometric deviations in timber components. The workflow includes camera-to-robot calibration, point cloud acquisition, robust detection of workpiece features, and precise alignment of the WCS. Experimental validation confirms that the proposed method is efficient and improves milling accuracy. By dynamically identifying the workpiece geometry, the system successfully addresses challenges posed by irregular timber shapes, resulting in higher accuracy for timber joints. This method contributes to advanced manufacturing strategies in robotic timber construction and supports the processing of diverse workpiece geometries, with potential applications in civil engineering for building construction through the precise fabrication of structural timber components. Full article

This study evaluates the effectiveness of rigid node connection prototypes for joining bamboo, in response to the growing need for sustainable construction solutions. Considering the superior mechanical properties of bamboo, including its flexibility and strength, the research focuses on the design and testing of nine connection prototypes subjected to compression, shear, and tensile tests in a laboratory. The results obtained demonstrate that the prototypes significantly exceed the established minimum strength criteria, with average maximum loads of 62.19 kN in compression tests, 10.16 kN in shear tests, and 25.41 kN in tensile adhesion tests. These findings not only confirm the viability of bamboo as a sustainable construction material but also highlight the need to develop efficient connection methods that integrate bamboo’s flexibility with the strength of other materials. Through these connections, bamboo presents itself as a solid alternative to address housing deficits and promote responsible construction practices. The research suggests continuing additional studies to strengthen knowledge about bamboo’s behavior in different construction contexts, thereby contributing to a more sustainable future in building. Full article

End-users can design personalized furnishing products using remote web-based CAD systems. However, if these designs fail to incorporate design for disassembly (DfD) principles, the furniture’s subsequent repair, reconfiguration, recycling, and disposal can be significantly hindered. To address this drawback, this study supports DfD, a strategy that enables the creation of easily repairable, reusable, and recyclable furniture to reduce waste and environmental impact. Consequently, this review aims to classify and evaluate available furniture joinery systems for their suitability within DfD frameworks, ultimately promoting their implementation within CAD environments. To this end, various solutions were evaluated, including traditional joints, dowel/biscuit, hammered, directly screwed, snap-on, expandable, and cam/bolt fasteners. Based on a literature review and practical observations, the analyzed joinery systems were categorized into non-disassemblable, conditionally disassemblable, and fully disassemblable categories. Only the fully disassemblable solutions effectively align with DfD principles. The study postulates a preference for expandable and cam/bolt fasteners in furniture designs, noting that although snap-on fasteners can potentially support DfD, this outcome is not always ensured. To guarantee that the designed furniture adheres to the DfD principles, the following eight furniture design guidelines were formulated: develop web-accessible disassembly instructions, prioritize access to fast-wearing components, prioritize modularity, standardize parts in modules, label components, enable independent component removal, use materials that withstand repeated disassembly, and employ fully disassemblable joints. Full article

Building materials, including polyvinyl chloride (PVC), play a key role in construction engineering, influencing the durability, esthetics, and functionality of structures. PVC stands out for its lightness, thermal insulation, and corrosion resistance. This makes it competitive with wood, aluminum, or steel, particularly in the manufacture of window joinery. One of the key technological processes in the processing of PVC profiles is welding, the quality of which depends on the precise control of parameters such as the temperature, time, and pressure regulating the speed of the welding heads. In modern welding machines, the use of servo drives guarantees the adequate precision and repeatability of the process, which allows better adjustment to technological requirements than in older machines. This study aimed to determine the effect of the heating head feed rate for selected milling depths on the quality and strength of window frame welds. A criterion in the assessment of the strength of the window frames was the result of failure load tests on the welds. In addition, the tests took into account the quality of the welds. The tests showed that the welding head feed rate of 0.25 mm/s generated the highest-quality welds, taking into account the continuity and symmetry of the weld and its highest failure load. When milling the composite to a depth of 1 mm, the average value of the failure load was 3637 N. Meanwhile, for speeds of 0.19 mm/s and 0.31 mm/s, it was 3157 N and 3033 N, respectively. For the 0.5 mm milling variant and without milling the composite, the average load values were significantly smaller. Full article

This study is based on the Taihang Mountain Area in Southern Hebei Province, focusing on battlefield sites in She County. Interdisciplinary theories and methods such as field investigation, architectural typology, and GIS spatial analysis are used to establish the protection roadmap and geographic information database for battlefield sites. The aim is to reveal the architectural characteristics and spatiotemporal distribution patterns of battlefield sites, evaluate its current status and constraints, and propose targeted protection strategies and restoration measures. Research has found that battlefield sites combine the characteristics of traditional dwellings and village temples, presenting the characteristics of clear clustering distribution and low altitude with a system near the water in the spatial and temporal dimensions, with good natural adaptability and unique rural cultural landscapes. At the same time, in response to the constraints and challenges still faced by protection work, a protection strategy framework has been constructed from six aspects: strengthening daily maintenance, reducing human and natural damage, optimizing the property rights system, unifying responsibility subjects, comprehensive development and utilization, and international legislation and cooperation. Repair and protection guidelines have been established from five technical links: timber structure, joinery work, roof, wall, and ground. This study can lay the foundation for the cultural inheritance and sustainable protection of battlefield sites in the Taihang Mountain Area of Southern Hebei Province, and provide theoretical references and practical examples for similar research. Full article

The aim of the study was to identify limiting factors for reusing wood through the recycling of window frames by conducting research under fully controlled conditions. The research involved manufacturing new window frames, seasoning them, and then shredding them into wood particles to prepare a three-layer particleboard. The proportion of wood particles in recycling was 0, 5, 10, 25, 50, and 100 parts by weight of the manufactured particleboard. Mechanical property tests were conducted: modulus of elasticity (MOE) and modulus of rupture (MOR), internal bond (IB), screw withdrawal resistance (SWR), and physical properties: density profile (DP), thickness swelling (TS) after water immersion, water absorption (WA), as well as formaldehyde emission and total volatile organic compound (TVOCs) tests. The research indicates a significant potential for utilizing wood from this sector of the wood industry, particularly considering variants with a higher proportion of recycled wood. MOR and MOE results are most promising for variants above 50 parts by weight of recycled wood. Based on the results obtained, it is clear that the production process should be improved or the raw material modified to enhance the internal bonding of particleboard, as these results were the weakest. Thus, recycled wood from window joinery has the potential to be reincarnated as particleboard, which continues to be widely used in their production. Full article

This article discusses research on the low-temperature pyrolysis of waste floor and furniture joinery as an example of chemical recycling. Pyrolysis was carried out at 425 °C to obtain solid, liquid, and gaseous products. In line with the circular economy concept, the waste was transformed into economical and environmentally friendly raw materials suitable for application. Research results related to the chemical composition and properties of pyrolysis products are shown, with particular emphasis on the migration process of acidic impurities, i.e., sulphur and chlorine. In some processes, the presence of such substances can be a problem. Research has shown the high potential for sulphur and chlorine migration in pyrolysis products. It was shown that for woodwork, the most sulphur was discharged with the pyrolysis gas and the least was immobilised in the oil fraction. For vinyl panels, more than 50% of the sulphur was immobilised in the char. Chlorine was immobilised mainly in the char and pyrolysis gas. A high chlorine content of 12.55% was found in the vinyl panel. At the same time, a high chlorine content was also found in the pyrolysis products of these panels. This value is several times higher than in wood-based waste. Full article

In the field of construction, human-robot collaboration and mixed reality (MR) open new possibilities. However, safety and reliability issues persist. The lack of flexibility and adaptability in current preprogrammed systems hampers real-time human-robot collaboration. A key gap in this area lies in the ability of the robot to interpret and accurately execute operations based on the real-time visual instructions and restrictions provided by the human collaborator and the working environment. This paper focuses on an MR-based human-robot collaboration method through visual feedback from a vision-based collaborative industrial robot system for use in wood stereotomy which we are developing. This method is applied to an alternating workflow in which a skilled carpenter lays out the joinery on the workpiece, and the robot cuts it. Cutting operations are instructed to the robot only through lines and conventional “carpenter’s marks”, which are drawn on the timbers by the carpenter. The robot system’s accuracy in locating and interpreting marks as cutting operations is evaluated by automatically constructing a 3D model of the cut shape from the vision system data. A digital twin of the robot allows the carpenter to previsualize all motions that are required by the robot for task validation and to know when to enter the collaborative workspace. Our experimental results offer some insights into human-robot communication requirements for collaborative robot system applications in timber frame construction. Full article

Limited empirical and qualitative studies focus on the detailed processes and obstacles for coordinating off-site prefabrication between builders and suppliers. This research aims to identify and address the obstacles that currently prevent the further expansion of off-site prefabrication, with a research scope on timber and mechanical/electrical/plumbing (MEP) services in construction projects. The focal point of this research is to highlight their obstacles. A total of forty interviews were conducted and analyzed from four builders’ organizations and four suppliers’ organizations to ascertain their obstacles in coordinating the practice of off-site prefabrication. The results found the builder’s obstacles were sustainability, quality assurance (QA), mass production, CAD/BIM, technological support, commercial arrangements, system building, buffering in supply, schedule monitoring, productivity, flexibility, engagement, risks, and multiple supply arrangements. The supplier’s obstacles were design, financing and subcontracting, coordination, recognized practices, risks, multiple supply arrangements, and constraints. Moreover, the builders and suppliers had identified some ways to harmonize off-site prefabrication of timber. Some examples of timber prefabrication technology include joinery, doors and/or windows, structural floor/wall/roof frames, partitions, trusses, stairs, balustrades, and others. MEP services with in situ construction comprise the use of power sources and working coordination. The most important outcome of this investigation is that these obstacles can be addressed through collaboration and coordination. This is because there is a traditionally a lack of collaboration amongst builders and their suppliers. Furthermore, there is a lack of coordination between them in general. The research contributes to the improved timber and MEP services collaboration and coordination in off-site prefabrication, which can be referred to by other approaches of modular construction. Full article

This study is intended to assess the types of joints applied in the Joinery Category of the Regional Taiwan Skills Competitions (hereafter referred to as the Regional Competitions, including Northern Taiwan, Central Taiwan and Southern Taiwan). The authors use a self-developed derivation calculation formula (${\displaystyle \sum }_{i=1}^n{w\times h}_i$) to examine the differences in the types of joints applied. Then a regression equation is adopted to estimate the distribution of weight values of the joint types to calculate the assessed values of the joint types likely to be used in the Regional Competitions of the 51st Taiwan Skills Competition. Subsequently, the similarity of the fuzzy number is employed to understand the tendency in the development of joint types from the 36th Regional Competition to the 50th Regional Competition. The outcome shows that 19 types of joints were applied and the assessed value of 2.3 of open bevel mortise-tenon joints was the highest, followed by the 2 of bevel inclined mortise-tenon joints and the 0.73 of sloped haunch mortise-tenon joints. Meanwhile, the application of similarity of triangular fuzzy numbers to examine the 19 types of mortise-tenon joints indicates that the area of the affiliation map of open bevel mortise-tenon joints is the largest. Compared to the other 18 types of mortise-tenon joints, the assessed value of level of similarity is the lowest. In other words, the assessed values acquired by using the similarity of triangular fuzzy numbers and by using the derivation calculation formula have the same tendency. Hence, it is suggested that when trainers/instructors determine training strategies, they should adopt open bevel mortise-tenon joints, bevel inclined mortise-tenon joints and sloped haunch mortise-tenon joints to be the assessment standards. At the same time, they can also use the affiliation map of similarity of triangular fuzzy numbers to evaluate the differences between various types of mortise-tenon joints to understand the tendency of joint type development. Thus, the teaching quality of trainers/instructors and the learning results of contestants can both be upgraded. Systematic approaches also have to be consolidated to strengthen the ability to assess vocational education and training (VET) in order to improve the learning effects and technical capacity of Joinery category contestants. It is hoped that the derivation calculation formula can be applied to evaluate the training of Joinery category contestants in regional competitions to improve the quality of VET. Full article

Wood is a truly sustainable and aesthetically pleasant material used in indoor and outdoor applications. Every material, including wood, is expected to have long-term durability and to retain its original appearance over time. One of the major disadvantages of wood is the deterioration of its surface when exposed outdoors, known as weathering. Although weathering is primarily a surface phenomenon, it is an important issue for wood products as it affects their appearance, service life, and wood-coating performance. To encourage the use of wood as a material for joinery and other building components, the results of research into increasing the weathering resistance of wood are extremely significant. The development of weathering protection methods is of great importance to reduce the maintenance requirements for wood exposed outdoors and can have a major environmental impact. There are various methods of protecting wood surfaces against weathering. This paper provides a literature survey on the recent research results in protecting wood from weathering. The topics covered include surface treatments of wood with photostabilizers; protection with coatings; the deposition of thin film onto wood surfaces; treatments of wood with inorganic metal compounds and bio-based water repellents; the chemical modification of wood; the modification of wood and wood surfaces with thermosetting resins, furfuryl alcohol, and DMDHEU; and the thermal modification of wood. Full article

Lean production principles have greatly contributed to the efficient and customer-oriented mass production of goods and services. A core element of lean production is the focus on cycle times and designing production controls and buffers around any bottlenecks in the system. Hence, a production line organized by lean principles will operate in a static or at least quasi-static way. While the individualization of products is an interesting business approach, it can influence cycle times and in-time production. This work demonstrates how performance losses induced by highly variable cycle times can be recovered using a digital twin. The unit under analysis is an industrial joiner’s workshop. Due to the high variance in cycle time, the joinery fails its production target, even if all machines are below 80% usage. Using a discrete event simulation of the production line, different production strategies can be evaluated efficiently and systematically. It is successfully shown that the performance losses due to the highly variable cycle times can be compensated using a digital twin in combination with optimization strategies. This is achieved by operating the system in a non-static mode, exploiting the flexibilities within the systems. Full article

The aim of the article is to present the results of preliminary research of the defects in residential buildings occurring during the warranty period. Due to the small amount of data, the research results cannot be generalized but allow for the formulation of research hypotheses that will be verified in future studies. The data collected included reports of defects in three multifamily residential buildings constructed by the developer in one of the big cities in Poland, which were then examined. For the examination of defects, statistical analysis was used, which revealed that more than half of the reports contained reasonable defects. The results of the preliminary research also indicate that, on the one hand, owners are very active in making warranty claims in the first three months from the date of commissioning, and, on the other hand, with time, the percentage of reasonable defects increases. In terms of the significance of defects, the largest percentage was significant defects. The results showed little activity on the part of property managers in the initial phase of the operation of the buildings, which is the opposite of that of apartment owners. Reports of faults in windows and door joinery, moisture, scratches on walls, and in the area of balconies and terraces are characterized by a relatively low number of cases reported in the first half of the year after the building is commissioned and a gradual increase in the subsequent warranty period. On the other hand, reports related to electrical installation defects are most frequent in the initial period of the warranty, but, with time, their number decreases. Full article