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The transient loads on the spherical hybrid sliding bearings (SHSBs) rotor system during the process of accelerating to stable speed are related to time, which exhibits a complex transient response of the rotor dynamics. The current study of the shaft center trajectory of the SHSBs rotor system is based on the assumption that the rotational speed is constant, which cannot truly reflect the trajectory of the rotor during operation. The purpose of this paper truly reflects the trajectory of the rotor and further investigates the stability of the rotor system during acceleration of SHSBs.

The model for accelerated rotor dynamics of SHSBs is established. The model is efficiently solved based on the fourth-order Runge–Kutta method and then to obtain the shaft center trajectory of the rotor during acceleration.

Results show that the bearing should choose larger angular acceleration in the acceleration process from startup to the working speed; rotor system is more stable. With the target rotational speed increasing, the changes in the shaft trajectory of the acceleration process are becoming more complex, resulting in more time required for the bearing stability. When considering the stability of the rotor system during acceleration, the rotor equations of motion provide a feasible solution for the simulation of bearing rotor system.

The study can simulate the running stability of the shaft system from startup to the working speed in this process, which provides theoretical guidance for the stability of the rotor system of the SHSBs in the acceleration process.

This research purpose was to explore the meaning of historicism, architectural historicism, the architectural attributes, design principles, elements and ornamentations of churches in medieval Western architecture, and how they were reflected in contemporary churches' design in Jordan.

This research used the historical descriptive–interpretive qualitative research method. Around 24 Western medieval churches were selected, studied and analyzed to explore the common design attributes of each historical era. The design attributes of each era were segmented under three categories: Design principles (plans' typology, facades, shapes, details, composition and building form), design elements (openings, towers and entrances) and ornamentation (sculptures, paintings and interior decoration). Additionally, three modern Jordanian churches were analyzed using the same method to compare with the historical churches through personal observations, field trips, researchers' memories, site visits, archival records, plans, images, books, slides, details and note-making. Different types of evidence were used, such as determinate, contextual and inferential. In addition, different tactics for analysis were used in analyzing the historical churches: site familiarity, use of existing documents, virtual and visual inspection and comparison with conditions elsewhere. Credibility was achieved when the results were reviewed and compared with the original and similar information.

Early Christian design principles, elements and ornamentations were reflected in Jordanian churches more than in Byzantine, Renaissance, Romanesque and Gothic. The design principles of Western medieval architecture were reflected in the selected Jordanian churches more than in ornamentation and design elements. Moreover, this research found that the highest reflection of Western medieval architecture on Jordanian churches was in designing the plans, which is a basilica with a central nave and aisles followed by opening styles, façade, shapes, entrances design, composition, painting and the minimum reflection was in sculptures. Additionally, there was no reflection on tower design and interior decoration.

This research encourages architects to enhance architectural historicism by focusing on historical styles in contemporary designs and using design elements, principles and decorations of historical styles in medieval architecture to enrich the variety and originality of architectural design and create new modern stylistic architecture. Architectural historicism increases historical self-awareness and helps a generation of architects to answer the question: In what style should be built.

Learning the design principles, not copying the past, is becoming a trend for most architects. Architectural historicism introduces new temporal elements, gives a new meaning and primary function to architecture to become socio-temporal and contextual contrast and reflects the essential points of references of the past through design methodology to express the present. The advantage of this research is to put an end to architects' role in syncretism and subjectivism. Instead, historicism architects equipped with the necessary knowledge and supported by the published research and inventors of historical architecture, can choose, imitate, adapt, borrow and use the correct historical forms that originated in a given period.

The purpose of variable loading conditions (392 N-785N-392N-785N) with break-in period were used to study interactions between zinc dialkyl dithiophosphate (ZDDP) 0.1 P% (phosphorus) and fine-grade molybdenum disulfide (MoS₂) 3%, in different mixtures of NLGI 2 lithium stearate grease. Four-ball wear tests were used to evaluate the tribological properties of different grease mixtures such as coefficient of friction and wear. ASTM 2266 as reported by earlier studies is useful, but it is not representative of real-life applications where variable loads and speeds and different break-in periods play a role and could change the results and the nature of tribofilms.

In this study, chemical and mechanical properties of tribofilms were examined. Moreover, design of experiment was used to examine the data and shorten experimentation time. Research described here is investigating variable loading conditions for real-life applications by using a break-in period of 2 min at the start to minimize asperities and establish a clean surface. Design expert (DOE) analyzes responses to reveal those variables that are single factor and those that are multifactor whether synergistically or antagonistically.

The results indicated that spectrum loading with break-in period showed reduction in wear when tested in greases with ZDDP/MoS₂ combinations. Ramping up or down the load every 7.5 min for a rotational speed of 1,200 rpm and a total of 36,000 revolutions or 30-min time slowed the wear properties of lithium-based grease under different MoS₂ and ZDDP concentrations. Experiments indicated that wear was largely dependent on the loading condition and ZDDP additives during specific break-in period at 1,200 rotational speed. It is believed that MoS₂ greases perform better under spectrum loading and under constant loading when mixed with ZDDP phosphorus.

This research indicates that there is a synergistic interaction between ZDDP, MoS₂ and variable loading especially when a break-in period is applied. The results indicated that wear was largely dependent on the specific speed used with spectrum loading as presented in the energy dispersive spectroscopy and the Auger electron spectroscopy analysis, and thus a 3% MoS₂ grease with ZDDP (phosphorus: 0.1 Wt.%) are needed to improve the wear resistance and improve the friction characteristics.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0016/

Stab-resistant body armor (SRBA) is used to protect the body from sharp knives. However, most SRBA materials currently have the disadvantages of large weight and thickness. This paper aims to prepare lightweight and high-performance SRBA by 3D printing truss structure and resin-filling method.

The stab resistance truss structure was prepared by the fused deposition modeling method, and the composite structure was formed after filling with resin for dynamic and quasi-static stab tests. The optimized structural plate can meet the standard GA68-2019. Digital image correlation technology was used to analyze the local strain changes during puncture. The puncture failure mode was summarized by the final failure morphologies. The explicit dynamics module in ANSYS Workbench was used to analyze the design of the overlapped structure stab resistance process in this paper.

The stab resistance performance of the 3D-printed structural plate is affected by the internal filling pattern. The stab resistance performance of 3D-printed structural parts was significantly improved after resin filling. The 50%-diamond-PLA-epoxy, with a thickness of only 5 mm was able to meet the stab resistance standard. Resins are used to increase the strength and hardness of the material but also to increase crack propagation and reduce the toughness of the material. The overlapping semicircular structure was inspired by the exoskeleton structure of the demon iron beetle, which improved the stab resistance between gaps. The truss structure can effectively disperse stress for toughening. The filled resin was reinforced by absorbing impact energy.

The 3D-printed resin-filled truss structure can be used to prepare high-performance stab resistance structural plates, which balance the toughness and strength of the overall structure and ultimately reduce the thickness and weight of the SRBA.