Investigation of Active Disassembly in Large Force Applications

Active disassembly (AD) is an emerging field of research in design for disassembly that enables a cost-effective nondestructive separation of product components. It is based on using active joints and fasteners that enables the self-disassembly of products without any direct contact between the product and the operator, where these joints and fasteners must be inserted in the product during its design and manufacturing phases. Generally, active joints and fasteners are made of smart materials such as shape memory alloys (SMAs), that can generate the necessary disassembly forces required to separate the different components of the product. Most of the exerted effort in this field of research was focused on separating products requiring small disassembly forces either in the electronic or automotive sectors. All these active disassembly applications were based on using shape memory alloy snap fits, clips, or wires that are characterized by their ability to generate small forces with large displacements. As, up to the authors knowledge, none of the exerted efforts were concerned with investigating the possibility of using the large disassembly forces that could be generated using shape memory alloy actuators in large force active disassembly applications. Consequently, the presented research aims to examine the possibility of applying active disassembly with products requiring large disassembly forces, having tapered surfaces and large mechanical structure. By presenting two case studies to validate the possibility of using active disassembly with large force applications, in addition to investigating the capability of using shape memory alloy actuators assembled either concentric or eccentric with the product structure.

Length regulation of multiple flagella that self-assemble from a shared pool of components

The single-celled green algae Chlamydomonas reinhardtii with its two flagella—microtubule-based structures of equal and constant lengths—is the canonical model organism for studying size control of organelles. Experiments have identified motor-driven transport of tubulin to the flagella tips as a key component of their length control. Here we consider a class of models whose key assumption is that proteins responsible for the intraflagellar transport (IFT) of tubulin are present in limiting amounts. We show that the limiting-pool assumption is insufficient to describe the results of severing experiments, in which a flagellum is regenerated after it has been severed. Next, we consider an extension of the limiting-pool model that incorporates proteins that depolymerize microtubules. We show that this ‘active disassembly’ model of flagellar length control explains in quantitative detail the results of severing experiments and use it to make predictions that can be tested in experiments.