Browse Topic: Geometric design and tolerancing (GD&T)
In the 1990s and early 2000s, the field of parallel kinematics was viewed as being potentially transformational in manufacturing, having multiple potential advantages over conventional serial machine tools and robots. Many prototypes were developed, and some reached commercial production and implementation in areas such as hard material machining and particularly in aerospace manufacturing and assembly. There is some activity limited to niche and specialist applications; however, the technology never quite achieved the market penetration and success envisaged. Yet, many of the inherent advantages still exist in terms of stiffness, force capability, and flexibility when compared to more conventional machine structures. This chapter will attempt to identify why parallel kinematic machines (PKMs) have not lived up to the original excitement and market interest and what needs to be done to rekindle that interest. In support of this, a number of key questions and issues have been identified
Additive manufacturing (AM) is currently being used to produce many aerospace components, with its inherent design flexibility enabling an array of unique and novel possibilities. But, in order to grow the application space of polymer AM, the industry has to provide an offering with improved mechanical properties. Several entities are working toward introducing continuous fibers embedded into either a thermoplastic or thermoset resin system. This approach can enable significant improvement in mechanical properties and could be what is needed to open new and exciting applications within the aerospace industry. However, as the technology begins to mature, there are a couple of unsettled issues that are beginning to come to light. The most common question raised is whether composite AM can achieve the performance of traditional composite manufacturing. If AM cannot reach this level, is there enough application potential to warrant the development investment? The answers are highly
The dimensional quality of the car body is built on quality management of form, fitment, and functional requirements. Each of these attributes reflects the final product quality and, therefore, needs to be ascertained quantitatively. Design intent and functionality conformance with specifications are paramount to performance, and thus quality. It is accomplished through optimal Geometric Dimensioning and Tolerancing of parts (GD&T), datum/Primary Locating Points (PLP) strategy, tricks/levers, and assembly design. Challenges stem from the complexity involved in the datum layout strategy and its optimization for desired deviations. Incorrect datum schemes in design prompt underconstrained fixtures, redundant datum, the sensitivity of datum layout, etc. and induce defects in later stages. The end effect is smoothing out the variation issues leading to compromise in quality. Hence, robust datum schemes and checks become imperative for high-quality standards, and keep components within
To provide the curved hose industry and their customers with a recommended practice for applying GD&T procedures to curved hoses and to provide generic curved hose drawings that represent the application of GD&T to typical curved hose parts. Dimensioning and Tolerancing will be in accordance with ASME Y14.5M
As the brake industry moves completely into globalization, a standardized method to define and validate the dimensions of backing plates, in a way that is both clear and feasible, is of critical importance for manufacturers at all tiers. The plate drawing not only defines the component as it fits into a brake assembly; it is also what the plate supplier relies on to define the plate for manufacture. If a drawing does not define every dimensional aspect of the product with perfect clarity, in ways that are easily measured, loss of time and resources will result from questions and/or mistakes. This paper proposes an SAE standard for defining the dimensional requirements of backing plates on the drawings themselves, and defining the measuring procedures used to validate those dimensions. The proposed standard employs already established methods such as geometric dimensioning and tolerancing (GD&T), including instruction on its proper application to features specific to backing plates
Residual brake torque (RBT) is generated in disc brakes as a result of contact between brake disc and brake pads when the braking pressure is not applied. Among the negative implications of RBT are, notably, dispensable additional fuel consumption as well as increased pad (taper) wear. Several properties of the brake system have a direct influence on the level of residual torque [1]. A major effect is connected to the caliper properties determining the clearance gap. This is characterized by the default air gap between pads and disc and its distribution regarding vehicle inner and outer sides (piston and fist sides for floating type calipers). Initial air gap is mainly influenced by the sealing grove design (between piston and housing, where the sealing ring is positioned). The retraction of the piston due to the sealing ring, also called rollback, mainly depends on the load case (e.g. applied pressure and temperature). Insufficient air gap will lead to residual clamping forces between
Conventionally, the engines are calibrated under the assumption that engines will be made exactly to the prints, and all the engines from the same batch will be identical. However, engine-to-engine variations do exist which will affect the engine performances, and part-to-part variations, i.e., the tolerance, is an important factor leading to engine-to-engine variations. There are researches conducted on the influence of dimensional tolerances on engine performance, however, the impact of straightness, which is an important geometric tolerance, on lubrication is an unsolved issue. This study presents a systematic method to model the straightness and to analyze its effects on the friction loss. The bearing model is built based on elastohydrodynamic (EHD) theory. Meanwhile a novel modeling method to represent any form of straightness in three-dimensional space is proposed. Then the meta-model with straightness as the input and friction loss as the output is built based on Kriging
3D digitalization and modeling is very popular in industrial applications such as metrology, geometric dimensioning and tolerancing (GD&T) and tridimensional object inspection. The 3D captured data can be used for the inspection of object surfaces. However, hidden defects cannot be detected with this technology. In order to get this kind of information, NDT/E (Non-Destructive Testing/Examination) approaches are used (ultrasounds, infrared imaging, etc.). These two types of information are very important in aerospace products inspection (e.g. composite materials). The two modalities (3D Vision and NDT) are still used separately. In this work, we present a new multi-modal fusion framework for combining these two data types. The fusion scheme works on 3D image data and temporal thermal images in order to obtain a hybrid model for simultaneously inspecting the 3D surface and the hidden sub-surface defects. The proposed system permits an augmented visualization of structural non visible
The parabolic leaf spring plays a vital role in suspension systems, since it has an effect on ride comfort and vehicle dynamics. Primarily, leaf spring endurance must be ensured. Presently, there are two approaches to designing a leaf spring. In the traditional method, fatigue tests should be repeated for each case, considering different material, geometry and suspension hard points. However, it takes a long time and requires a heavy budget to get the optimized solution. In the contemporary method, a numerical approach is used to obtain the fatigue life and the leaf geometry against the environmental condition on the basis of material properties. This paper presents a more precise method based on non-linear finite element solutions by evaluating the effects of the production parameters, the geometrical tolerances and the variations in the characteristics of the material. In other words, it is a hybrid method, a blend of the traditional and the recent ones, which correlates the real
The automotive industry is one of the drivers of CAE-based virtual product development. Due to a highly competitive market, development of innovative, high quality products within a short time is necessary and it is only possible by using virtual prototyping. It is important to note that increased application of virtual prototyping itself increases the necessity to perform robustness studies. If the number of hardware tests has to be reduced, it is essential to implement the scatter, which is always present in these tests (such as loads, material, geometry), into the computational model. Consequently, probabilistic methods using CAE-based stochastic analysis have to be utilized in order to quantify robustness, safety and serviceability. Brake noise is one of the most important problems in the automobile industry due to the high warranty costs. The generation of brake noise is due to the development of instabilities in the brake system. The analysis of brake squeal is highly complex and
To provide the curved hose industry and their customers with a recommended practice for applying GD&T procedures to curved hoses and to provide generic curved hose drawings that represent the application of GD&T to typical curved hose parts. Dimensioning and Tolerancing will be in accordance with ASME Y14.5M
To provide the curved hose industry and their customers with a recommended practice for applying GD&T procedures to curved hoses and to provide generic curved hose drawings that represent the application of GD&T to typical curved hose parts. Dimensioning and Tolerancing will be in accordance with ASME Y14.5M
To provide the curved hose industry and their customers with a recommended practice for applying GD&T procedures to curved hoses and to provide generic curved hose drawings that represent the application of GD&T to typical curved hose parts. Dimensioning and Tolerancing will be in accordance with ASME Y14.5M
Items per page:
50
1 – 50 of 65