Disassembly Analysis Research Articles

Selective disassembly for virtual prototyping as applied to de-manufacturing

Selective disassembly involves separating a selected set of components from an assembly. Applications for selective disassembly include de-manufacturing (maintenance and recycling), and assembling. This paper presents a new methodology for performing design for selective disassembly analysis on the CAD model of an assembly. The methodology involves the following three steps: (i) identifying the components to be selectively disassembled for de-manufacturing by a software program or designer, (ii) determining an optimal (e.g. minimal cost) disassembly sequence for the selected components that involves a computationally efficient two-level reduction procedure: (a) the determination of a set of sequences with an objective of minimal component removals via a wave propagation approach that topologically order components in an assembly for selective disassembly, and (b) the evaluation of resulting sequences based on an objective function (e.g. minimal cost) to identify an optimal sequence, and (iii) Performing disassembly design decisions based on the evaluated optimal sequence. Preliminary implementation results of the selective disassembly methodology in sequencing and disassembly cost evaluation, and application of the selective disassembly technique for de-manufacturing assessment are presented.

Economical evaluation of disassembly operations for recycling, remanufacturing and reuse

This paper introduced a procedure which integrates economical factors into the scheduling of disassembly operations for Material Recovery Opportunities (MRO). MRO are defined as opportunities to reclaim post-consumer products for recycling, remanufacturing and reuse. Traditionally, recyclers have resorted to using heuristics for analysing the breakdown of products and the associated costs. In this paper, a quantitative method of disassembly analysis is developed. Its aim is to improve the efficiency of the disassembly planning process and to generate an optimal disassembly sequence which maximizes profit. Three economic indices are used to evaluate the trade-off between reclamation and disposal of individual components. A systematic procedure of generating an optimal disassembly sequence based on maximizing the profits of material recovery is presented. Three criteria are established to reduce the search space and facilitate recovery opportunities: (1) material compatibility, (2) clustering for disposal, and (3) concurrent disassembly operations. An example is provided on a product being disassembled for recycling at a local recycling plant in Canada.

A framework for virtual disassembly analysis

Product reuse or recyclability is enhanced by designing the product for inexpensive and efficient disassembly. However, accomplishing enhanced product design requires design for disassembly (DFD) tools. This paper presents a disassembly framework that consists of design modules; both of these are embodied in the geometric DFD tool. These modules consist of different tasks including: selection of the appropriate disassembly method; producing an optimized disassembly sequence; evaluating a disassembly sequence for cost; producing design change recommendations. These considerations make a product easier to disassemble and therefore have potential benefit to the environment.

Simulation, animation, and analysis of design disassembly for maintainability analysis

SUMMARY Designing mechanical systems for efficient disassembly improves their maintainability. Issues related to design disassembly for maintainability analysis of an evolving mechanical system design are discussed. Procedures and methodologies for the identification of disassembly sequence, animation of human technicians in performing the disassembly sequence, tool selection, time and cost analysis, and human factors analysis of the disassembly sequence are presented. Their software implementation in a maintainability analysis workspace is described and illustrated using a maintenance task example.

A substructure-frontal technique for cantilever erection analysis of cable-stayed bridges

A substructure-frontal technique for the analysis of the sequence of planar partial structures which arise during the cantilever erection of a cable-stayed bridge is presented. A computer code which implements the static analysis for such sequences is described. A forward process of substructure assembly is combined with a frontal elimination of condensable degrees of freedom in such a way that the reduced stiffness matrix for each partial structure is stored and easily accessible for disassembly analysis or for investigation of alternative erection sequences. Cable and P- Δ nonlinearities, and the discrete steps in the assembly or disassembly of any individual substructure are included. The program is designed for implementation on an AT-type microcomputer and graphically displays result at all stages of the erection process.

An integrated computer aid for generating and evaluating assembly sequences for mechanical products

An integrated computer aid that is useful for assembly-line design and for concurrent design of mechanical products is described. Recognizing that early consideration of assembly sequence is important for producibility, quality control, flexibility, and market responsiveness, the authors have built an integrated set of user-interactive computer programs that generates all feasible assembly sequences for a product and then aids the user in judging their value based on various criteria. The programs use a disassembly analysis for generating sequences and provide online visual aids during generation and evaluation. During evaluation, matters such as avoiding difficult assembly states or moves, stability, fixturing, orientation, refixturing and reorientation count, and inclusion of favorable states are considered to highlight desirable or undesirable sequences. The designer edits the set of sequences according to these criteria, leading to an informed sequence choice or to needed design refinement. The interactive programs provide a rapid means for sequence selection, encouraging their use during early design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A fractionated cell-free system for analysis of prophase nuclear disassembly.

We describe a cell-free system in which a postribosomal supernatant (s140) from metaphase Chinese hamster ovary (CHO) cells induces prophase-like changes in isolated CHO cell nuclei, including chromatin condensation, and nuclear envelope and lamina disassembly. These events are strongly promoted by gamma-S-ATP and an ATP-regenerating system, and do not take place with an s140 derived from G2-phase cells. The metaphase cell s140 also induces disassembly of an isolated nuclear lamina fraction that is depleted of membranes, chromatin, and nuclear pore complexes. Disassembly of the isolated lamina is accompanied by phosphorylation of the major lamina proteins (lamins A, B, and C) to levels characteristic of metaphase cells. Kinetic analysis of lamina depolymerization indicates that cooperativity may be involved in this process. The biochemical properties of in vitro lamina disassembly suggest that the activity that depolymerizes the lamina during mitosis is soluble in metaphase cells, and support the notion that this activity is a lamin protein kinase.

The Influence of Particle Phase Size on the Disassembly Accident Transient in Fast Reactors

Two-phase dispersed-flow regimes have often been hypothesized for the disassembly analysis of hypothetical core disruptive accidents in fast reactors. The influence of particulate phase size on the power transient is examined. In general it is observed that the bigger the particle size the larger the energy release during the disassembly phase. The dependence of the power transient on the particle size itself depends on the drag force expression. The Stokes term and form factor of the drag force try to enforce a somewhat different particle size dependence. A flatter flux distribution decreases this dependence significantly. The choice of the equation of state also affects this dependence.

Explosive Disassembly of Fast Reactors

Theoretical analysis of the explosive disassembly of fast reactors, following accidental loss of coolant and melting and gravity compaction of the fuel material,has been undertaken. A general expression for the rate of reactivity feedback dueto material disassembly in a core with more than one enrichment zone has been derived. Energy release in cylindrical geometry has been calculated with the effects due to zonal interfaces properly considered in the limit of zero acoustic speeds. The effect on the energy release of the assumption of fixed fuel density in the fuel equation-of-state has been investigated for oxide-fueled zoned cores.Fuel zoning can result in either greater or less energy release, as compared with a homogeneous core of the same fuel inventory and the same initial conditions, depending on the gradient of the density worth function at the zonal interface. In some large fast breeder reactors the gradient of the density worth function may be negative at the zonal interface. The positive pressure gradient at the interface during the disassembly phase of a transient results in inwardly directed fuel displacement at the interface and in a positive contribution to the disassembly reactivity feedback. Typically, this can increase the energy released in a disassembly transient by as much as 35%. The effect on energy release of the assumption of fixed fuel density in the fuel equation-of-state was not significant for the transients initiated in the completely molten sodium-free reactor cores studied in this investigation.

Disassembly Sequence Analysis ForEnvironmentally Conscious Design And Manufacturing

Environmentally conscious design and manufacturing (ECDM) is becoming a very important issue in the manufacturing community. Adequate product reuse and recycling can greatly reduce waste generation, thus increasing product environmental compatibility. Design for disassembly analysis is a building block of the ECDM system. It is able to design or redesign products so that a higher percentage of the component parts can be reused or recycled. In this study, an economic model of disassembly analysis is formulated and integrated with an object oriented product model. Due to the nonlinear and combinatorial characteristics of the problem, a simulated annealing algorithm is employed to find the economically optimal sequences that yield the maximum return value, and to advise where the disassembly operation should stop. It shows the potential of analyzing the environmental friendliness of material selection, assembly configuration, and fastening methods. The proposed method is illustrated with a water pump assembly example.