Fatigue Analysis of Dozer Push Arms under Tilt Bulldozing Conditions

Tilt bulldozing generates unbalanced loads on two push arms, which leads to the service lives of the two push arms being different. Because the push arms rotate in triaxial directions during tilt bulldozing, it is difficult to accurately analyze the fatigue life of the push arm with one specific boundary condition and loading history. Therefore, a fatigue analysis of the push arms under tilt bulldozing conditions is proposed based on co-simulation of RecurDyn-EDEM-AMESim in this paper. The control of tilt bulldozing conditions is realized automatically according to the tilt angle and blade depth. The dynamic loads of the push arms are accurately calculated in this virtual model. Subsequently, the stress–time histories are obtained to investigate the fatigue lives of push arms. Both the overall damage and the initiation positions of the cracks are predicted herein. It is determined that the fatigue lives of the right and left push arms are 7,317.84 h and 39,381.89 h, respectively. Thus, the life of the push arm on the blade’s tilted side is reduced by 81.42% compared to the other side. Additionally, experimental tests are conducted to verify the accuracy of the virtual model. Analysis results indicate that the strains of the push arms according to the virtual simulation are close to those measured in the experiments.

Accuracy of full-arch digitalization for partially edentulous jaws — a laboratory study on basis of coordinate-based data analysis

Objectives To compare the accuracy (trueness and precision) of direct digitization of four different dental gap situation with two IOS (intraoral scanner). Materials and methods Four partially edentulous polyurethane mandible models were used: (1) A (46, 45, 44 missing), (2) B (45, 44, 34, 35 missing), (3) C (42, 41, 31, 32 missing), and (4) D (full dentition). On each model, the same reference object was fixed between the second molars of both quadrants. A dataset (REF) of the reference object was generated by a coordinate measuring machine. Each model situation was scanned by (1) OMN (Cerec AC Omnicam) and (2) PRI (Cerec Primescan AC) (n = 30). Datasets of all 8 test groups (N = 240) were analyzed using inspection software to determine the linear aberrations in the X-, Y-, Z-axes and angular deviations. Mann–Whitney U and two-sample Kolmogorov–Smirnov tests were used to detect differences for trueness and precision. Results PRI revealed higher trueness and precision in most of the measured parameters ($${\overrightarrow{V}}_{E}$$ V → E 120.95 to 175.01 μm, $$\overrightarrow{V}_{E}$$ V → E (x) − 58.50 to − 9.40 μm, $$\overrightarrow{V}_{E}$$ V → E (z) − 70.35 to 63.50 μm), while OMN showed higher trueness for $$\overrightarrow{V}_{E}$$ V → E (y) regardless of model situation (− 104.90 to 34.55 μm). Model D revealed the highest trueness and precision in most of the measured parameters regardless of IOS ($$\overrightarrow{V}_{E}$$ V → E 120.95 to 195.74 μm, $$\overrightarrow{V}_{E}$$ V → E (x) − 9.40 to 66.75 μm,$$\overrightarrow{V}_{E}$$ V → E (y) − 14.55 to 51.50 μm, $$\overrightarrow{V}_{E}$$ V → E (z) 63.50 to 120.75 μm). Conclusions PRI demonstrated higher accuracy in the X- and Z-axes, while OMN depicted higher trueness in the Y-axis. For PRI, Model A revealed the highest distortion, while for OMN, Model B produced the largest aberrations in most parameters. Clinical relevance Current results suggest that both investigated IOS are sufficiently accurate for the manufacturing of tooth-borne restorations and orthodontic appliances. However, both hardware specifications of IOS and the presence of edentulous gaps in the dental model have an influence on the accuracy of the virtual model dataset.

BIM Structural Project Applied in A Case Study: Interoperability Analyses, Reinforcement Detailing Drawings and Quantity Take-off

Background: The Building Information Modelling (BIM) methodology has been acquiring, worldwide, a growing acceptance in all sectors of the Construction industry, and the study intends to contribute to its implementation within the structural design. The fundamental concept of BIM is based on the generation of a centralized virtual model with all information concerning different specialties. This is supported in efficient interoperability, but within the structural design, this aspect is difficult to achieve completely, as currently, the interoperability of this system is still inefficient. Introduction: This study intends to analyze the degree of interoperability verified in the development of all the processes (modelling, transposition, structural analyses and reinforcement detailing) involved in a structural design using BIM tools. Methods: A structural project concerning a study case was performed in order to identify benefits and limitations, based on the consistency analysis of the transposed data between systems, Revit and Robot, in all steps required in a BIM process. This text describes the stages of modelling, checking the suitability of the analytical model, its transference to the analysis tool in order to proceed with the structural calculations and detailing drawings and, finally, the transfer of drawings to the main BIM model. Results: The limitations verified in the last stage were partially surpassed with complementary work enabling the automatic transfer of drawings and quantities of materials. In addition, the study explores new capacities of BIM, namely, the extraction of information allowing the presentation of specific drawings and maps of the geometry of the reinforcement rods. Conclusion: This study identifies a working strategy that leads to an appropriate use of BIM software contributing to the optimization of labor in a structural office.

Development of a Standardised Process of Scenario Writing Through a Virtual Assistant Model in Nursing Teaching

Background: The use of simulation allows students to develop skills. Simulation in the teaching of clinical skills is preceded by some stages, the first of which requires the development of a scenario. This study aimed to develop and test a virtual model for creating scenarios for realistic simulation, focusing on the person with dependence in self-care activities. Methods: A methodological study was conducted in two phases. The first phase of the study aimed to analyse and propose the structure and functioning of the virtual assistant for scenario creation through the nominal group’s technique, involving a group of 10 experts. The second, a quasi-experimental study without a control group, with 128 second-year students, in the four-year nursing degree course, who participated in two moments of realistic simulation, one with a traditional scenario and the other with a scenario built through the virtual assistant. The students completed a questionnaire to assess their understanding of the data, suggested interventions, and their contribution to learning after each simulation experience. Results: The group of experts identified the fields and key concepts that should be part of the structure of the scenarios and proposed a set of icons for better visual recognition of the information. Students considered that the new scenario template favoured their understanding of the situation under analysis and the recognition of the focuses of attention that they should prioritise for the elaboration of the intervention plan. Conclusions: A virtual role-play assistant model for a standardized process of scenario writing to help realistic simulation in nursing teaching is a novelty in this study likely to contribute to learning gains.

Digital Twin-Assisted Simulation of Complex Assembly Models in Descending Process and Implementation of Key Link Characterization

In this paper, the simulation and key link characterization of the complex assembly model step-down process are studied and analysed in depth using the digital twin approach, and the method is used in the practical process. The physical model step-down method MORA algorithm and its physical interpretation in various simplified cases are given, and the MORA method is improved on this basis. The concept of local activeness based on knot structure is introduced, and the process of model transformation and downscaling and decomposition based on local activeness is explained in detail. The high-fidelity mapping of solid equipment is completed in virtual space, which can accurately reproduce and predict the health state of engineering equipment throughout its life cycle, effectively avoiding the huge property losses and safety risks caused by early failure of vulnerable structures and providing a safe and stable working environment for offshore oil and gas production. With the prototype monitoring data as reference, the response surface method is used to identify the parameters of the finite element model of the hinge node, which improves the fidelity of the virtual model of the hinge node. Considering the friction coefficient changes and load characteristics during the degradation of the hinge node, the dynamics simulation conditions are set, and the operating states of the hinge node at different stages of its whole life cycle are simulated by using the high-fidelity virtual model of the hinge node, and the prediction model of the hot spot stress of the hinge node is established to monitor its in-position state in real time, and the operation and maintenance overhaul method based on the health state of the hinge node is proposed. The system is divided into four modules: multilevel inverse modelling of the assembly twin, statistical shape characterization and analysis of batch parts, optimization of fixture positioning and flexible assembly of thin-walled parts, and optimization of low-stress assembly of bolted joint structure, which verifies the feasibility of the method and provides guidance for the actual product forming process.

Development of a wearable orthotic device pattern to prevent hip dislocation in children with cerebral palsy

PurposeThis study suggest the development of a wearable orthotic device pattern that can reduce pain and deformation, and help in the normal development of children with cerebral palsy. Such a pattern enables daily wear before hip subluxation occurs, to prevent hip dislocation and subluxation.Design/methodology/approachThis study set the design line by carrying out cell work on the actual model, then proceeded with the first pattern design. The final version of the second orthotic device was designed by conducting discussions with experts and the patient's guardian, with the device fitted to the child patient. The evaluation of the second orthotic device used the virtual model to check the pressure area and level through virtual fitting. An evaluation was then conducted with the device fitted to the child patient, to verify the functionality and suitability of the final pattern.FindingsFollowing the initial fitting evaluation, the second pattern was presented after modifying and supplementing issues such as movement suitability with posture change, position change of the great trochanter when wearing a diaper, pressure control of the X-shaped band on the genital area and thigh abduction. The master pattern of the final version of the second orthotic device was proposed after confirming that the femoral head of the hip joint was stably fixed, and the compression was applied through a verification based on the virtual fitting using the virtual model, and with the device fitted to the child patient.Originality/valueWith this study, it is expected that the process and design plan for the development of wearable orthotic device patterns for the persons with disabilities impaired mobility can be used as a basic resource to create devices that merge the clothing and medical fields.

Adequate BIM level of detail for LCA energy simulation

<p>This research tested the new LCAQuick Residential, a computer-based analysis tool developed by BRANZ (available from www.branz.co.nz). This tool is designed to allow the ready preparation of a LCA at an early point in the design process for a residential house. The research problem was created by the infancy of the program and its unknown ability to produce results to support decision making to include Life Cycle Analysis (LCA) for designers and developers seeking a more sustainable design outcome. The method of testing was to take a real house design and model it using Autodesk Revit™ to create a virtual model. The virtual model was then used to input material quantities into LCAQuick Residential, which in turn generated a full set of Life-Cycle Energy (LCE) data. To test this approach, the data from a Quantity Surveyor (Schedule of Quantities) was also used as input to LCAQuick Residential, and the results compared. For this research on the energy component of LCA was examined – the LCE. It was found that the material quantities generated by each of the approaches differed, and it was necessary to critically compare them to ensure material volumes, density and quantity were appropriately matched and entered into the tool. Considerable care was also required to ensure materials were correctly identified and allocated to the appropriate LCAQuick library material.</p>

Adequate BIM level of detail for LCA energy simulation

<p>This research tested the new LCAQuick Residential, a computer-based analysis tool developed by BRANZ (available from www.branz.co.nz). This tool is designed to allow the ready preparation of a LCA at an early point in the design process for a residential house. The research problem was created by the infancy of the program and its unknown ability to produce results to support decision making to include Life Cycle Analysis (LCA) for designers and developers seeking a more sustainable design outcome. The method of testing was to take a real house design and model it using Autodesk Revit™ to create a virtual model. The virtual model was then used to input material quantities into LCAQuick Residential, which in turn generated a full set of Life-Cycle Energy (LCE) data. To test this approach, the data from a Quantity Surveyor (Schedule of Quantities) was also used as input to LCAQuick Residential, and the results compared. For this research on the energy component of LCA was examined – the LCE. It was found that the material quantities generated by each of the approaches differed, and it was necessary to critically compare them to ensure material volumes, density and quantity were appropriately matched and entered into the tool. Considerable care was also required to ensure materials were correctly identified and allocated to the appropriate LCAQuick library material.</p>

Simulation of the Vibrations Produced to the Human Body During Operation of the Bucket Wheel Excavators. A Case Study of ERc 1400-30/7 Type Excavator

The paper deals with the analysis of the dynamic response over time of the excavator boom during operation. For a start, we determined the variation in time of the forces acting on the rotor shaft, due to the excavation. These forces have high values and a slow variation over time, which depends on the rotation speed of the bucket wheel and the number of buckets installed on it. A virtual model of the BWE boom was proposed, for which the dynamic response in time due to the excavation forces was determined, for a point in the main cabin of the BWE. A virtual sensor has been attached to this point corresponding to seat of the operator. The simulation of the dynamic response over time was performed taking into account a global damping of 2% of the critical damping. The simulation was performed both for the excavation of a homogeneous material and for the case of a shock (a sudden appearance of an inclusion of hard material during the cutting of the homogeneous material).