Rock drilling rigs are widely used in tunnel construction, Their work flow is divided into positioning drill arm and drilling the rock. During rock drilling, the thruster supports the rock drill to start drilling. At this time, the impact frequency of the drill tool of the rock drill is as high as 40-60 Hz, which causes the vibration of the drill arm and then affects the positioning of the thruster, and further affects the quality of the hole. The flexible drill boom model is imported into ADAMS for rigid-flexible coupling analysis and to explore the influence of the drill arm vibration on the thruster. When analyzing the vibration reduction optimization of the thruster, the optimization object is the rubber top plate of the thruster. The rubber constitutive model with high fitting accuracy at the operating frequency of the rock drill is selected.
Strategies for evaluating the impact of mission requirements on the design of mission‐specific vehicles are needed to enable project managers to assess potential benefits and associated costs of changes in requirements. Top-level requirements that cause significant cascaded difficulties on lower‐level requirements should be identified and presented to decision-makers. This paper aims to introduce formal methods and computational tools to enable the analysis and allocation of mission requirements and associated key performance indicators (KPI). Three interrelated research problems are identified to achieve the discussed objectives: (1) understanding the current practices of the requirements elicitation process using a case study approach; (2) identifying inter‐relationship between mission definitions and technology infusion using gamification strategies; and (3) representing the technical requirements computationally and identifying their inter-relationships.
Robotic technology has begun to play an essential role in ground automotive applications. Utility trucks are among the first responders in extreme climate and severe weather conditions, comprised of two systems: a mobile platform and an articulated robotic morphing arm. The conventional industrial manipulators are mounted on stationary bases, while a mobile manipulator is dynamically coupled on a mobile platform. Such trucks with morphing manipulator can increase the possibility of road accidents in many ways and, additionally, create dangerous situations on the roads, and off-road conditions, while moving, and performing tasks. Large boom equipped trucks for reaching elevated heights can become unstable due to drastic variation of the boom equipment moment of inertia causing the extreme weight re-distribution among the wheels. The morphing capabilities of the utility trucks need to be investigated together with the vehicle-road forces in order to hold the truck safe on the roads.
Eigenvalues of a simple rotating flexible disk-shaft system are obtained using different methods. The shaft is supported radially by non-rigid bearings, while the disk is situated at one end of the shaft. Eigenvalues from a finite element and a multi-body dynamic tool are compared against an established analytical formulation. The Campbell diagram based on natural frequencies obtained from the tools differ from the analytical values because of oversimplification in the analytical model. Later, detailed whirl analysis is performed using AVL Excite multi-body tool that includes understanding forward and reverse whirls in absolute and relative coordinate systems and their relationships. Responses to periodic force and base excitations at a constant rotational speed of the shaft are obtained and a modified Campbell diagram based on this is developed. Whirl of the center of the disk is plotted as an orbital or phase plot and its rotational direction noted.
Nyquist plots are a classical means to visualize a complex vibration frequency response function. By graphing the real and imaginary parts of the response, the dynamic behavior in the vicinity of resonances is emphasized. This allows insight into how modes are coupling, and also provides a means to separate the modes. Mathematical models such as Nyquist analysis are often embedded in frequency analysis hardware. While this speeds data collection, it also removes this visually intuitive tool from the engineer’s consciousness. The purpose of this paper is to review the fundamentals of Nyquist plots and their application to structural vibration. The behavior of a single degree of freedom system will be shown to be well described by a circle on its Nyquist plot. This observation allows simple visual examination of the response of a continuous system, and the determination of quantities such as uncoupled natural frequencies, modal damping factors, and uncoupled modes shapes.
The driving power system can be combined with lasers, lights, etc., and applied to automobiles to achieve various functions. Under the general trend of the development of intelligent vehicles, people have higher and higher requirements for the accuracy and power of various equipment. Therefore, it is extremely important to study and design a high-power drive system in this paper, so as to ensure a stable output of a certain value of current. The system is composed of power supply, load, secondary power supply and control chip. The secondary power supply adopts BUCK type circuit and cooperates with synchronous rectifier chip. The control part uses two PID control algorithms. After the MATLAB and Multism simulations, the experimental part is expanded, and the results show that the linearity is only 0.82%, the return error tends to zero, and the maximum accuracy error is 0.02V, which basically meets the requirements and has a certain practicability.
Safety assurance is a central concern for the development and societal acceptance of automated driving (AD) systems. Perception is a key aspect of AD that relies heavily on Machine Learning (ML). Despite the known challenges with the safety assurance of ML-based components, proposals have recently emerged for unit-level safety cases addressing these components. Unfortunately, AD safety cases express safety requirements at the system-level and these efforts are missing the critical linking argument connecting safety requirements at the system-level to component performance requirements at the unit-level. In this paper, we propose a generic template for such a linking argument specifically tailored for perception components. The template takes a deductive and formal approach to define strong traceability between levels. We demonstrate the applicability of the template with a detailed case study and discuss its use as a tool to support incremental development of perception components.
A parametric tool is developed to design general purpose and medium duty digging buckets for excavator. This is an excel based tool linked with CREO using VB API Toolkit feature of CREO. Critical parameters in determining lift ratio (such as vehicle tonnage, OEM bucket details, OEM maximum lift at full reach etc.) are defined as input parameters in the excel. Formulae set in this excel are used to calculate lift ratio which is used to determine if this newly developed bucket can be used with specified vehicle tonnage. It will auto generate 3D CAD model and 2D print in PDF format. This tool will also help to standardize the design process. Further, the developed 3D model is analysed in ANSYS to check if stresses induced in bucket due to its working conditions are less than the material limit thereby assessing the robustness of design. Thus, it will help to reduce turn around time for design iterations.
The Tobyhanna Army Depot (TYAD) COMSEC Forward Repair Activity (FRA) Van enhances the U.S Army Communications Security (COMSEC) readiness by bringing TYAD COMSEC supply and maintenance capabilities to the operational theater. Each COMSEC FRA Van maintains pre-determined stock to offer unit customers for direct exchange (DX), which permits the Warfighter to have functioning equipment immediately instead of waiting for assets to arrive through standard supply channels. Additionally, the COMSEC FRA Van technicians can receive and repair COMSEC items promptly. Since 2005, the TYAD COMSEC FRA Vans have DX’d or repaired over 23,000 COMSEC items in the operational theaters of Germany, Korea, Kuwait, and Afghanistan. The TYAD COMSEC FRA Vans ensure minimal downtime occurs during supply and maintenance actions allowing units to continue their mission and not risk enemy forces accessing sensitive communications.
Electroimpact provides a solution of a gantry riveting machine which works in cooperation with a wing panel fixture. The fixture features stringer clamps along the length but also needs to reconfigure so that fasteners can be accessed by the heads of the machine. In a recent development we have made the header boards of the fixture both narrow in width and shallow in depth. This has a large operational advantage. Almost all of the fasteners can be installed without disturbing the tooling. And the motions of the tooling are considerably reduced. This was a cooperative effort of the tooling designers and the machine designers, primarily on the stringer side of the panel. How much of a time savings does this provide in comparison with the previous approach? About 20%. This paper will explain how this was done. We have already implemented this solution on ten systems and more are in progress on major aircraft programs.
There are at least three significant cost driving problems with the lamination of modern composite aerospace components. These problems are exaggerated for high production rate systems but affect all forms of automated fiber placement style lamination. 1) The amount and cost of capital equipment is extremely high. 2) The input costs are very high. 3) Autoclaves are huge and expensive and Airframers seem to dislike them a great deal. This paper’s topic will address the problems associated with item 1) Excessive capital equipment due to poor utilization of AFP equipment and the steps recently taken to increase it by a factor of at least 4. We will explain how the quality systems in place structurally hold our AFP equipment to such low utilization and explain how AFP4.0 addresses these factors.
AS13100 AESQ Quality Management System Requirements for Aero Engine Design and Production Organizations Standard was created to replace customer specific quality requirements – leading to simplification and harmonization between engine manufacturer supply chains. AS13100 is supported by a series of 13 AESQ Reference Manuals (RM) that provide additional detail on certain subjects to describe the intent of the standard and to provide guidance on deployment. The Reference Manuals are designed to enable the supply chain to deploy the AS13100 requirements efficiently and effectively. The AESQ RMs provide case studies, guidance material, forms and checklists specific to each section of the standard to aid the user with implementation.