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This paper aims to develop a method to improve the accuracy of tolerance analysis considering the spatial distribution characteristics of part surface morphology (SDCPSM) and local surface deformations (LSD) of planar mating surfaces during the assembly process.

First, this paper proposes a skin modeling method considering SDCPSM based on Non-Gaussian random field. Second, based on the skin model shapes, an improved boundary element method is adopted to solve LSD of nonideal planar mating surfaces, and the progressive contact method is adopted to obtain relative positioning deviation of mating surfaces. Finally, the case study is given to verify the proposed approach.

Through the case study, the results show that different SDCPSM have different influences on tolerance analysis, and LSD have nonnegligible and different influence on tolerance analysis considering different SDCPSM. In addition, the LSD have a greater influence on translational deviation along the z-axis than rotational deviation around the x- and y-axes.

The surface morphology with different spatial distribution characteristics leads to different contact behavior of planar mating surfaces, especially when considering the LSD of mating surfaces during the assembly process, which will have further influence on tolerance analysis. To address the above problem, this paper proposes a tolerance analysis method with skin modeling considering SDCPSM and LSD of mating surfaces, which can help to improve the accuracy of tolerance analysis.

Virtual product design has become a key technology in reducing costly design errors that are often difficult to detect manually. In order to evaluate product assembly in a virtual environment, it is important to link a product's design in CAD with the constrained complexity of assembly operations in CAM so that the design can be evaluated and modified in a virtual environment before production begins. The paper aims to focus on this.

The proposed virtual system includes the following components: a product assembly coding model, named Open Structured Assembly Coding System (OSACS), that codes part‐mating operations for assembling any two parts in CAM; a rule‐based code extractor that identifies OSACS codes for assembling product from the part‐mating information encoded in Standard for the Exchange of Product Model Data AP‐203 CAD data; and an assembly‐sequence generator that generates a binary assembly‐tree for the designed product coded with OSACS assembly codes, representing assembly operations in CAM for product assembly.

The proposed system links the design phase in CAD with the manufacturing phase in CAM. Simulation studies were made using CAD Ap‐203 data files from an actual mobile phone housing assembly. A binary assembly‐tree assigned with OSACS assembly codes was generated for assembling the product. The assembling complexity between any two parts was coded with the unique OSACS assembly codes. The final binary assembly tree represents how the product is going to be assembled in CAM with the mating complexity encoded in the assigned OSACS codes.

The advantage of this virtual product assembly system is that a design can be validated first in a virtual environment without building the expensive physical production system. Moreover, additional design iterations can be performed in the same amount of time to improve product quality.

Linking product design in CAD with assembly operations in CAM can help realize significant cost savings by preventing future manufacturing problems. With the proposed virtual system, a company can prevent a potential problematic design from reaching production.

This paper introduces the conceptual design of a virtual system that links product design in CAD with assembly operations in CAM. This system provides a designer with a virtual product assembly process to evaluate a designed product.

This paper aims to distinguish the relationship between the morphology characteristics of different scales and the contact performance of the mating surfaces. Also, an integrated method of the spectrum analysis and the wavelet transform is used to separate the morphology characteristics of the actual machined parts.

First, a three-dimensional (3D) surface profilometer is used to obtain the surface morphology data of the actual machined parts. Second, the morphology characteristics of different scales are realized by the wavelet analysis and the power spectral density. Third, the reverse modeling engineering is used to construct the 3D contact models for the macroscopic characteristics. Finally, the finite element method is used to analyze the contact stiffness and the contact area of the 3D contact model.

The contact area and the nominal contact pressure Pn have a nonlinear relationship in the whole compression process for the 3D contact model. The percentage of the total contact area of the macro-scale mating surface is about 70 per cent when the contact pressure Pn is in the range of 0-100 MPa, and the elastic contact area accounts for the vast majority. Meanwhile, when the contact pressure Pn is less than 10MPa, the influence factor (the relative error of contact stiffness) is larger than 50 per cent, so the surface macro-scale morphology has a weakening effect on the normal contact stiffness of the mating surfaces.

This paper provides an effective method for the multi-scale separation of the surface morphology and then lays a certain theoretical foundation for improving the surface quality of parts and the morphology design.

The traditional precision design only takes the influence of geometric tolerance of the parts and does not involve the load deformation in the assembly process. This paper aims to analyze the influence mechanism of flexible parts deformation on the geometric precision, and then to ensure the reliability and stability of the mechanical system.

Firstly, this paper adopts the N-GPS to analyze the influence mechanism of flexible parts deformation on the geometric precision and constructs a coupling 3D tolerance mathematical model of the geometric tolerance and the load deformation deviation based on the SDT theory, homogeneous coordinate transformation theory and surface authentication idea. Secondly, the least square method is used to fit the deformation surface of the mating surface under load so as to complete the conversion from the non-ideal element to the ideal element.

This paper takes the horizontal machining center as a case to obtain the deformation information of the mating surface under the self-weight load. The results show that the deformation deviation of the parts has the trend of transmission and accumulation under the load. The terminal deformation cumulative amount of the system is up to –0.0249 mm, which indicated that the influence of parts deformation on the mechanical system precision cannot be ignored.

This paper establishes a comprehensive 3D tolerance mathematical model, which comprehensively considers the effect of the dimensional tolerance, geometric tolerance and load deformation deviation. By this way, the assembly precision of mechanical system can be accurately predicted.

This paper aims to comprehensively achieve the requirements of high assembly precision and low cost, a precision-cost model of assembly based on three-dimensional (3D) tolerance is established in this paper.

The assembly precision is related to the tolerance of parts and the deformation of matching surfaces under load. In this paper, the small displacement torsor (SDT) theory is first utilized to analyze the manufacturing tolerances of parts and the assembly deformation deviation of matching surface. In the meanwhile, the extracting method of SDT parameters is proposed and the assembly precision calculation model based on the 3D tolerance is established. Second, an integrated optimization model based on the machining cost, assembly cost (mapping the deviation domain to the SDT domain) and quality loss cost is built. Finally, the practicability of the precision-cost model is verified by optimizing the horizontal machining center.

The assembly deviation has a great influence on cost fluctuation. By setting the optimization objective to maximize the assembly precision, the optimal total cost is CNY 72.77, decreasing by 16.83 per cent from the initial value, which meets economical requirements. Meanwhile, the upper bound of each processing tolerance is close to the maximum value of 0.01 mm, indicating that the load deformation can be offset by appropriately increasing the upper bound of the tolerance, but it is necessary to strictly restrict the manufacturing tolerances of lower parts in a reasonable range.

In this paper, a 3D deviation precision-cost model of assembly is established, which can describe the assembly precision more accurately and achieve a lower cost compared with the assembly precision model based on rigid parts.

The ring seal under consideration has come out as a result of the complex research such as the numerical simulation research, introductory quality research involving a real object, comparative research on a tribotester and fundamental research on the real object. It has been found that the essence of excellent tribological properties of the new ring seal lies, in its low value of surface free energy (SFE) of titanium nitride coating on the piston ring and in its high value of energy which is the characteristic of the nitrided surface of the cast iron cylinder sleeve. As a result, when the motion of the ring on the sleeve surface ceases, especially in the outer dead centre (ODC) in expansion stroke, the boundary layer of oil on the sleeve surface prevents metallic contact. In general, it has been found that the SFE can be an important index of material selection for cutting pairs, especially for those working in the reciprocating motion.

This paper aims to propose and implement an integrated augmented-reality (AR)-aided assembly environment to incorporate the interaction between real and virtual components, so that users can obtain a more immersive experience of the assembly simulation in real time and achieve better assembly design.

A component contact handling strategy is proposed to model all the possible movements of virtual components when they interact with real components. A novel assembly information management approach is proposed to access and modify the information instances dynamically corresponding to user manipulation. To support the interaction between real and virtual components, a hybrid marker-less tracking method is implemented.

A prototype system has been developed, and a case study of an automobile alternator assembly is presented. A set of tests is implemented to validate the feasibility, efficiency, accuracy and intuitiveness of the system.

The prototype system allows the users to manipulate and assemble the designed virtual components to the real components, so that the users can check for possible design errors and modify the original design in the context of their final use and in the real-world scale.

This paper proposes an integrated AR simulation and planning platform based on hybrid-tracking and ontology-based assembly information management. Component contact handling strategy based on collision detection and assembly feature surfaces mating reasoning is proposed to solve component degree of freedom.

The information and knowledge about a product and its assembly are necessary to generate all feasible assembly sequences of that product. Assemblies contain a very large amount of information and complex relationships. Identifying assembled parts as well as their contact surfaces is very important in design and manufacturing since this information is essential. The problem is to not only make the information available but also use the relevant information for making decisions, especially determination of the optimum assembly sequence. This paper aims to address these issues.

This paper describes a system for processing assembly models and extracting assembly related data using application programming interface (API) of the computer‐aided design (CAD) software. These data are used to identify the relationships between different components of an assembly thus encouraging generation of feasible assembly sequences.

Instead of total human interpretation of the assembly design, a direct CAD database interface approach has been proposed to extract the relation with minimal manual involvement. The information extracted is used to generate a list describing the links between the assembled parts, the involved features and the type of link explicitly to facilitate assembly analysis and planning.

The methodology of using the API of the CAD modeling package SolidWorks, is a novel approach in which the assembly mate information is captured. Instead of total human interpretation of the assembly design, a direct CAD database interface approach has been proposed to extract the relation with minimal manual involvement.

Suggests that, without question, while every step in a systematic approach to the design of parts for assembly using integral snap‐fit features is important, none is more important than selecting locking features. After all, it is these features that hold the assembly together. While quite different in appearance and details of their operation, all integral locking features comprise a latch and a catch component to create a locking pair. Proper, no less optimum, function requires that such locking pairs be selected using a systematic approach. Presents that approach as a six‐step methodology, but first, defines and describes latch and catch components, bringing order to their apparent boundless variety. Demonstrates the utility of the methodology with a real‐life case study.

Virtual assembly process plays an important role in assembly design of complex product and is typically time- and resource-intensive. This paper aims to investigate a dynamic assembly simplification approach in order to demonstrate and interact with virtual assembly process of complex product in real time.

The proposed approach regards the virtual assembly process of complex product as an incremental growth process of dynamic assembly. During the growth process, the current-assembled-state assembly model is simplified with appearance preserved by detecting and removing its invisible features, and the to-be-assembled components are simplified with assembly features preserved using conjugated subgraphs matching method based on an improved subgraph isomorphism algorithm.

The dynamic assembly simplification approach is applied successfully to reduce the complexity of computer aided design models during the virtual assembly process and it is proved by several cases.

A new assembly features definition is proposed based on the notion of “conjugation” to assist the assembly features recognition, which is a main step of the dynamic assembly simplification and has been translated into conjugated subgraphs matching problem. And an improved subgraph isomorphism algorithm is presented to address this problem.