Mechanical Design Requirements Research Articles

Thermal optimization of a high heat load liquid-metal-bath cooled mirror at the Hefei Advanced Light Facility.

Within the beamlines of diffraction-limited storage rings, the liquid-metal-bath cooling scheme is a prevalent choice for the cooling of high-heat load mirrors. This study employs the finite element analysis method to evaluate the thermal deformations of liquid-metal-bath horizontally deflecting mirrors in the Hefei Advanced Light Facility. In particular, we introduce a novel optimization strategy to obtain the optimal thermal deformation scenario, which also satisfies mechanical design requirements. Moreover, a concurrent optimization approach across multiple structural parameters of mirrors is adopted to attain globally optimal thermal deformation. Following the optimization of the mirror's structural parameters, the curvature radius increases to 227 km, while the residual slope error decreases to 36.3 nrad at 6eV in the meridian direction. The ray tracing analysis of the beam demonstrates a considerable reduction in the influence of thermal deformation on the beam's focal point. This work proposes an optimization method for designing cooling schemes under mechanical constraints.

Design and analysis of mechanical mechanism of cold-forming equipment for marine profiles

Abstract For the existing cold bending machine with complex structure, low automation, and poor motion accuracy. A cold-forming machine that can be used for cold-forming processing of ship profiles is designed in this paper. Firstly, the general structure of the equipment is described. Secondly, the key mechanical structures, such as the guiding mechanism, the feeding mechanism, and the cold bending mechanism, are explained. Finally, the finite element models of key components were mechanically analyzed. The results show that the mechanical structure design proposed in this paper not only meets the mechanical design requirements needed for the system but also can effectively prevent the profile from slipping during the feeding process and achieve highly accurate automatic cold bending processing of the profile.

Optimization analysis of thermal–hydraulic features of the 2.5 MW LBE spallation target of CiADS

In an Accelerator Driven System (ADS), the spallation target typically has a power of several megawatts or above. As high-power targets are challenging to design, the targets studied in the past generally had a power of 2 MW or less. For the China initiative Accelerator Driven System (CiADS) under construction, a 2.5 MW lead–bismuth eutectic (LBE) target is planned. In this paper, thermal–hydraulic and structural analyses were performed to optimize the design of the LBE spallation target. As a first step, given other conditions being fixed, the influence of a single parameter on the target performances, i.e., the outlet size, the diameter of the guide tube, the angle of the transition section, and the vertical distance from the origin of the beam window (BW) hemisphere to the upper end of the transition section, were investigated. Subsequently, the multi-factor analysis was conducted by adopting a four-factor and four-level orthogonal test. Results indicated that the target optimized by the multi-factor analysis, performed much better than the original design and that obtained by the single-factor analysis, providing a new approach for the parameter optimization of spallation target. Moreover, detailed analyses showed that the improved target met the thermal–hydraulic and mechanical design requirements.

Automatic Alignment of Fractured Femur: Integration of Robot and Optical Tracking System

This paper presents Robossis, a surgical robotic system for automated femur fracture alignment. Robossis is the integration of an optical tracking system with a 6-degree-of-freedom (6-DOF) 3-armed parallel robot that satisfies the clinical and mechanical design requirements for femur alignment surgery. In real-time, the optical tracking system obtains the spatial position of the distal and proximal parts of the fractured femur. Then, an auto-alignment algorithm uses this data to guide the robot to automatically and accurately align the bone fragments while overcoming the muscle payload surrounding the femur. A graphical user interface (GUI) provides a real-time visual guide for the surgeon to check the deviation from alignment while the robot is automatically bringing the bone into an aligned position. To demonstrate the capabilities of Robossis, laboratory and cadaver experiments are performed, showing that Robossis can successfully manipulate bone in 6 DOFs in space, achieving alignment with submillimeter accuracy.

JIP Focuses on Equipment Reliability in Subsea Production Systems

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30219, “SEAR JIP: A Success Story of Collaboration and How To Improve Equipment Reliability on Subsea Production Systems,” by Adriana Botto, Wood; Manish Tomar, Chevron; and Stuart Ferrier, ConocoPhillips, et al. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. The Subsea Equipment Australia Reliability (SEAR) joint industry project (JIP) is a partnership led by Wood with participation from a group of operators including Chevron Australia, ConocoPhillips, Inpex, Santos, Shell Australia, and Woodside. Now delivering Phase 6, the JIP is focused on collaboration and knowledge-sharing to improve the competitiveness of Australia’s oil and gas industry by addressing critical challenges associated with premature subsea-equipment failure. The complete paper provides an overview of the JIP and outlines lessons learned and value created. Background The SEAR JIP was initiated in 2014 with an aim of generating significant cost savings by improving subsea-equipment reliability and design for Australian operations, a goal best achieved through collaboration and knowledge-sharing. A reliability database was developed to collect offshore-operations failure information from SEAR members. The database provides a low-cost/high-value method of capturing lessons learned for subsea-equipment performance in Australia. A complementary test program, Transforming Australian Subsea Equipment Reliability (TASER), is under way to model innovative technologies under variable environments to validate equipment advancements. Phase 6 of the JIP aims to continue populating the reliability database while addressing two major industry challenges: the effect of marine fouling affecting equipment operability, and unwanted gas in subsea controls umbilicals. The outcome of this phase should provide opportunities for standardization, life extension, and development of new technologies. The JIP plans to issue an industry recommended practice in 2022 harnessing the lessons learned. This recommended practice will identify root causes of equipment failure and recommend material selection and mechanical design requirements for different environmental conditions. This will enable an improvement in equipment availability and a reduction in operating expenditures by minimizing offshore intervention to address failed equipment.

Novel Tube Design for Superheater Heat Exchanger Enabled Via Additive Manufacturing

Abstract Superheater tubes are critical boiler components that operate at relatively higher temperatures and pressure. Amongst the primary concerns for these tubes is the deposition of ash particles on the tube surface, leading to the reduced thickness of the tube due to material corrosion, consequently causing early creep failure of the component. In this research, a novel tube design has been proposed which resembles a teardrop or ogive shape to reduce the drag and concurrently improve the creep life of the superheater tubes. To administer the practicality of novel tubes, metal additive manufacturing (AM), for instance, laser-powder bed fusion (L-PBF), has been proposed. These unconventional designs were assessed and compared with the baseline circular tube design for mechanical design requirements (hoop stress and creep life) and the particle and flue gas flow characteristics around the differently shaped tubes. A thermomechanical finite element (FE) analysis was performed for hoop stress calculations. This study also emphasizes on effect of circumferential thermal variation on hoop stress distribution in tubes. Therefore, a detailed two-dimensional (2D) thermal simulation has been performed to report the circumferential thermal variation on the tube. A computational fluid dynamics (CFD) analysis coupled with particle tracing was performed for gas flow visualization and particle tracing around the proposed shapes and baseline circular-shaped tube design. The Schlieren optic setup was built and leveraged for qualitative validation of the proposed design. The complete design methodology established in the paper shows teardrop-shaped tubes better in terms of drag and creep life in contrast to the circular-shaped tube.

Design of a Smart Elbow Brace as a Home-Based Rehabilitation Device.

Poststroke and traumatic elbow injuries are the most common cause of elbow stiffness, which results in loss of functional range of motion (ROM). Various studies support early mobilization of the elbow joint after injury or after surgery to reduce risks of elbow stiffness development. After hospitalization, patients are required to follow a long-term rehabilitation program during home recovery. Still, most patients do not adhere to their clinical therapy schedule due to either rehabilitation cost, social obligations, negligence, or lack of inspiration. Moreover, the numbers of therapists and assessment equipment are insufficient. This study introduces a smart elbow brace (SEB) as a home-based rehabilitation device that reduces regular in-patient rehabilitation costs and therapist workload and motivates patients to comply with the rehabilitation program that enhances the achievement of rehabilitation goals. Our device has two active degrees of freedom (2-DoF) that allow extension, flexion, pronation, and supination elbow motions. An extra sliding joint between forearm and wrist is added, which helps dump forces concentration at the elbow joint during extension-flexion movement. Mechanical design requirements, motion-tracking systems, and serious game development are described. The feasibility of a proposed SEB device is tested with five healthy subjects playing developed serious games with the device. The results show that subjects can attain maximum and minimum angles of flexion-extension and pronation-supination motion designed for elbow stiffness rehabilitation. The SEB device will be beneficial and be used at home as a complementary tool to support elbow stiffness rehabilitation during long-term home recovery.

Biofabrication of tissue engineering vascular systems.

Cardiovascular disease (CVD) is the leading cause of death among persons aged 65 and older in the United States and many other developed countries. Tissue engineered vascular systems (TEVS) can serve as grafts for CVD treatment and be used as in vitro model systems to examine the role of various genetic factors during the CVD progressions. Current focus in the field is to fabricate TEVS that more closely resembles the mechanical properties and extracellular matrix environment of native vessels, which depends heavily on the advance in biofabrication techniques and discovery of novel biomaterials. In this review, we outline the mechanical and biological design requirements of TEVS and explore the history and recent advances in biofabrication methods and biomaterials for tissue engineered blood vessels and microvascular systems with special focus on in vitro applications. In vitro applications of TEVS for disease modeling are discussed.

Computationally Fast Dynamical Model of a SATCOM Antenna Suitable for Extensive Optimization Tasks

Development of new SATCOM (Satellite Communications) antennas and their control systems is a complex problem, in which strict requirements for mechanical design, drives, sensors and the overall speed and accuracy of the control algorithm must be met. Therefore, a simulation model is often used at different stages of development, which greatly accelerates the process of designing and optimizing the whole system. The computationally most demanding part of the simulation is the dynamical model of antenna. This article proposes an alternative approach for dynamical model creation, and the results are compared to a model created by using a universal multibody simulation environment. It is shown that the proposed new approach gives nearly the same-quality results and it is several times computationally faster.

Mechanical Design and Control Strategy for Hip Joint Power Assisting.

The basic requirements for mechanical design and control strategy are adapting to human joint movements and building an interaction model between human and robot. In this paper, a 3-UPS parallel mechanism is adopted to realize that the instantaneous rotation center of the assistive system coincides with human joint movement center, and a force sensory system is used to detect human movement intention and build the modeling of control strategy based on the interactive force. Then, based on the constructed experimental platform, the feasibility of movement intention detection and power assisting are verified through the experimental results.

Mechanical Analyses and Structural Design Requirements for Flexible Energy Storage Devices

AbstractFlexible energy storage devices with excellent mechanical deformation performance are highly required to improve the integration degree of flexible electronics. Unlike those of traditional power sources, the mechanical reliability of flexible energy storage devices, including electrical performance retention and deformation endurance, has received much attention. To provide the guideline for the construction design of devices, the strain distribution and failure modes in the entire architecture should be comprehensively investigated during mechanical deformation. This review mainly focuses on the mechanical deformation characterization, analysis, and structural design strategies used in recent flexible lithium‐ion batteries (LIBs) and supercapacitors (SCs). The primary theoretical calculation of bending strain in the devices is introduced first, and then several parameters to describe the bending status are summarized. Among those parameters, bending radius and its corresponding test methods and equipment are highlighted. Derivative strategies for structural design and an overview of their application progresses, such as selection of substrates, thickness of devices, employment of encapsulation, and novel architectural designs, are reviewed in detail. Finally, the challenges and prospects of flexible energy storage devices with reliable mechanical performance are discussed.

Concept design of the CFETR divertor remote handling system

The Chinese Fusion Engineering Testing Reactor (CFETR) is a superconducting tokamak fusion device envisioned to provide 200MW fusion power. Because of erosion with hazardous and/or activated dust (beryllium, carbon, tungsten) and tritium, the use of remote handling techniques will be eventually required. In particular, the replacement of components such as divertor modules will require the use of remote cutting, welding and inspection of cooling pipes. CFETR consists of 44 divertor (tow sizes) cassettes located in the bottom region of the vacuum vessel. The cassettes will be withdrawn from the vessel through four dedicated ports and transported to a hot cell for refurbishment and replacement during the reactor's operational lifetime. The divertor system remote replacement is one of the key maintenance operations for the CFETR due to the requirements of duty factor (0.3–0.5), machine safety, high plant availability and reliability. The critical issues such as the operational conditions (temperature, atmosphere, radiation, and contamination), maintenance functions, and mechanical design requirements of the divertor remote handling maintenance system (RHMS) are described. The concept design of the remote handling equipment, the operating procedures and the maintenance time estimations for high plant availability are also discussed in this paper.

On the relationship between ceramic strength and the requirements for mechanical design

Abstract During the last fifty years the mechanical properties of ceramic materials have been greatly improved, their toughness and strength have been increased and the scatter of strength decreased. Adequate statistical design procedures for brittle materials exist but cracking and brittle fracture of ceramic components still occur very often. In this review the theory of brittle fracture and the underlying assumptions are critically discussed and the measurement procedures of strength are reviewed. It is shown that the strength of materials, the strength of specimens and the strength of components are often quite different properties. Three main factors are identified which – in order to avoid unexpected failure of components – have to be considered much more than in the past: (i) hidden stresses, i.e. stresses caused by thermal strain mismatch, by contact (for example in joints) and internal stresses, (ii) the quality of the component's surfaces and edges and (iii) proper handling of ceramic materials and components. It can clearly be stated that the mechanical properties of many ceramic materials are appropriate even for applications under severe loading conditions but bad or incomplete mechanical design, insufficient surface finish and mishandling are the main reasons for unexpected failure of ceramic components.

Numerical simulations of heat transfer distribution of a two-pass square channel with V-rib turbulator and bleed holes

The blade tip region in gas turbine encounters high thermal loads due to temperature difference and hence efforts for high durability and safe operations are essential. Improved and robust methods of cooling are required to downgrade heat transfer rate to turbine blades. The blade tip regions, which are exposed to high gas flow, suffers high local thermal load which are due to external tip leakage. Jet impingement, pin cooling etc. are techniques used for cooling blades. A more usual way is to use serpentine passage with 180-degree turn. In this study, numerical simulation of heat transfer distribution of a two-pass square channel with rib turbulators and bleed holes were done. Periodical rib turbulators and bleed holes were used in the channel. The ribs arrangement were 60 degree V rib, 60 degree inverted V ribs, combination of 60 degree V rib at inlet and 60 inverted V rib at outlet section and combination of Inverted V at inlet and V rib at the outlet. The results were numerically computed using Fluent with Reynolds number of 12,500 and 28,500. Turbulence models used for computations were k-ω-SST and RSM. Temperature based and shear stress based techniques were used for heat transfer distribution prediction. The results for 60 degree V rib, 60 degree inverted V ribs were compared with the experimental results for validation of the results obtained. Detailed distribution shows distinctive peaks in heat transfer around bleed holes and rib turbulator. Comparisons of the overall performance of the models with different orientation of rib turbulator are presented. It is found that due to the combination of 60 degree inverted V rib in inlet and 60 V rib in outlet with bleed holes provides better heat treatment. It is suggested that the use of rib turbulator with bleed holes provides suitable for augmenting blade cooling to achieve an optimal balance between thermal and mechanical design requirements.

Study on Key Technology of Flatbed Inkjet Process and Equipment

Based on the flatbed inkjet printing technology development status at home and abroad, provided an overview of the flatbed inkjet device and technology principle, and introduced the required ink and plate. To focus on the flatbed inkjet device which the plate is fixed and the print head moves, put forward the mechanical design requirements. Besides, from the structure and layout of the device, elaborated the types of the flatbed inkjet device innovative ideas of design. Finally, summarized the advantages and disadvantages of the flatbed inkjet technology, and forecast its development prospects. To have some help in better understanding and application of flatbed inkjet technology.

Investigation of interconnect design on interfacial cracking energy of Al/TiN barriers under a flexural load

The integration of thin film technology into the fabrication of semiconductor transistors has given rise to significant challenges in the design of multi-level back-end-of-line interconnects. The interfacial adhesion between Al metal and TiN barrier is one of the major factors that affect interconnect reliability. Analyzing the effect of the interconnect structures of Al/TiN barriers on interfacial cracking energy under flexural loading is an interesting research direction. This work proposes a robust estimation of interfacial cracks by simulation-based methods to satisfy the mechanical design requirements for multi-level interconnect systems. A constant bending moment can be generated with the framework of the four-point bending test (4-PBT). A 4-PBT simulation model can be used in finite element analysis, combined with the J-integral method and the modified virtual crack closure technique, to accurately predict the interfacial fracture energy of Al/TiN films. Preliminary results indicate a considerable increase in energy release rate. Energy is released as a crack along the interface of the Al/TiN films passes through the region above the parallel metal lines of patterned interconnects, especially for a Cu/SiLK material system. The results also show that dielectrics can serve as stress buffer layers that inhibit crack growth.

Magnetic resonance imaging-compatible tactile sensing device based on a piezoelectric array

Minimally invasive surgery is a widely used medical technique, one of the drawbacks of which is the loss of direct sense of touch during the operation. Palpation is the use of fingertips to explore and make fast assessments of tissue morphology. Although technologies are developed to equip minimally invasive surgery tools with haptic feedback capabilities, the majority focus on tissue stiffness profiling and tool-tissue interaction force measurement. For greatly increased diagnostic capability, a magnetic resonance imaging-compatible tactile sensor design is proposed, which allows minimally invasive surgery to be performed under image guidance, combining the strong capability of magnetic resonance imaging soft tissue and intuitive palpation. The sensing unit is based on a piezoelectric sensor methodology, which conforms to the stringent mechanical and electrical design requirements imposed by the magnetic resonance environment The sensor mechanical design and the device integration to a 0.2 Tesla open magnetic resonance imaging scanner are described, together with the device's magnetic resonance compatibility testing. Its design limitations and potential future improvements are also discussed. A tactile sensing unit based on a piezoelectric sensor principle is proposed, which is designed for magnetic resonance imaging guided interventions.

Simulation governance: Technical requirements for mechanical design

Simulation governance is discussed from the perspectives of formulation and application of design rules in structural, mechanical and aerospace engineering. The key technical requirements are described in the context of what is variously called validation pyramid, building block method and validation experiment hierarchy and illustrated by an example.

Experimental Research on Seismic Behavior of Exterior Frame Joints with T-Shaped CFST Column and Steel Beam

In order to understand the mechanical performance and related tectonic design requirements of the concrete-filled steel tubular joints with special-shaped cross-section , three T-shaped concrete filled steel tubular column joints with exterior diaphragms were manufactured and experimented under cyclic loading. By changing the axial compression ratio of the columns and increasing the width and overhanging length of the stiffening ring, the hysteretic performance and working mechanism of such joints under cyclic loading were studied. The results show that by increasing the width and overhanging length of the stiffening ring, the hysteretic performance, ductility and energy dissipation capacity of joints were obviously improved.

Fabrication of compliant mechanisms on the mesoscale

Abstract. The fabrication of compliant mechanisms on the mesoscale requires collaboration of mechanical engineering design, with materials science and engineering fabrication approaches. In this paper, a review of current fabrication approaches to produce mesoscale devices is given, highlighting the benefits and limitations of each technique. Additionally, a hierarchy is provided, eliminating fabrication techniques that do not completely satisfy the mechanical design requirements of the compliant mechanisms. Furthermore, the lost mold-rapid infiltration forming process (LM-RIF) is described, and compared to existing fabrication approaches. Finally, prototype mesoscale compliant mechanisms are fabricated, demonstrating the versatility of the LM-RIF process to produce both metal and ceramic devices, as well as ability of a fabrication process to work in collaboration with mechanical design.