Peidong Han

Machining of Carbon Fiber Reinforced Plastics/Polymers: A Literature Review

Carbon fiber reinforced plastics/polymers (CFRPs) offer excellent mechanical properties that lead to enhanced functional performance and, in turn, wide applications in numerous industrial fields. Post machining of CFRPs is an essential procedure that assures that the manufactured components meet their dimensional tolerances, surface quality and other functional requirements, which is currently considered an extremely difficult process due to the highly nonlinear, inhomogeneous, and abrasive nature of CFRPs. In this paper, a comprehensive literature review on machining of CFRPs is given with a focus on five main issues including conventional and unconventional hybrid processes for CFRP machining, cutting theories and thermal/mechanical response studies, numerical simulations, tool performance and tooling techniques, and economic impacts of CFRP machining. Given the similarities in the experimental and theoretical studies related to the machining of glass fiber reinforced polymers (GFRPs) and other FRPs parallel insights are drawn to CFRP machining to offer additional understanding of on-going and promising attempts in CFRP machining.

Issues in Polycrystalline Diamond Compact Cutter–Rock Interaction From a Metal Machining Point of View—Part I: Temperature, Stresses, and Forces

This paper provides a comprehensive review of the literature that deals with issues surrounding the polycrystalline diamond compact (PDC) cutter–rock interface during rock cutting/drilling processes. The paper is separated into two parts addressing eight significant issues: Part I deals with fundamental issues associated with temperature/stress distribution and loading force prediction, while part II focuses on issues related to PDC cutter/bit performance, wear and other failure phenomena, rock removal mechanism and cutting theory, rock properties, and numerical modeling of cutter–rock interaction. Experimental, analytical, and numerical methods are included into the investigation of the abovementioned eight issues. Relevant concepts from metal cutting, micromachining, and other machining processes are also introduced to provide important insights and draw parallels between these interrelated fields. [DOI: 10.1115/1.4007468]

Issues in Polycrystalline Diamond Compact Cutter–Rock Interaction From a Metal Machining Point of View—Part II: Bit Performance and Rock Cutting Mechanics

In Part I of this paper, the issues related to temperature, stress and force were reviewed and parallels were drawn between both metal machining and rock cutting. Part II discusses the issues more directly related to polycrystalline diamond compact (PDC) bit performance and rock mechanics. However, relevant issues in various metal cutting processes will continue to be presented to clarify the gaps and similarities between these two classes of processes. [DOI: 10.1115/1.4007623]

Study of the effect of cannula rotation on tissue cutting for needle biopsy

Needle biopsy is a medical procedure to extract tissue for diagnosis of cancer and other diseases. The quality of tissue samples acquired by needle biopsy greatly depends on the cutting forces of the cannula. The reduction of cutting forces is crucial for obtaining good tissue samples. There exist many factors that influence the cutting forces, some of which include the cannula tip geometry, translation speed, and rotation speed. In the present paper, the effects of rotating the cannula on tissue cutting for needle biopsy are studied. A fracture-mechanics-based approach is used to analyze the cutting forces. Analysis has shown that the cutting forces decrease with the increases in the slice/push ratio defined as the ratio of speed component parallel to the cutting edge/speed perpendicular to the cutting edge. Experiments are performed to demonstrate this phenomenon. Mathematical models of the slice/push ratio for bevel tip cannulas are formulated. The results are used to determine the optimal cannula rotation/translation speed and the desired tip geometry for needle biopsy. It is shown that a minimal slice/push ratio of 2 is recommended. A cannula with a large bevel angle is more suitable for rotational needle biopsy.

Laser surface texturing of medical needles for friction control

Surface texturing has been used to create micro-dimples or micro-channels on medical needles to increase the visibility of ultrasound-guided percutaneous procedures. However, micro-features usually increase the friction between the needle and biological tissue. Higher insertion forces lead to patient discomfort and undesired needle placement errors. The present work investigates the friction between the textured needles and soft tissue. The purpose is to understand the friction behaviour between a textured hard surface and soft materials and to identify texture patterns that would minimise the friction of needle insertion without compromising its ultrasound visibility. Laser surface texturing was performed on medical needles to generate an array of micro-channels with a variety of channel widths, area densities, and channel orientations. A set of friction tests was carried out using an especially designed setup for needle insertion. The effects of channel width, area density, and channel orientation on friction force were experimentally investigated. It was found that the tribological characteristics between a textured hard surface and soft tissue greatly depend on the size, density, and orientation of the micro-features.

Contributions in medical needle technologies—Geometry, mechanics, design, and manufacturing

Abstract This article summarizes the contributions in research on tissue cutting with needles. The geometry of the needles cutting edges was analytically defined and expressions for the inclination and rake angles of hollow and solid needles and trocars have been derived. Based on the semi-empirical method, finite element model and the fracture mechanics approach, force models of needle insertion were developed. The relationship between the needles tip geometry and insertion force was established and used in several applications. It was shown, for example, that the cutting edge of the lancet needle can be optimally designed to minimize insertion force or bevel length. The cutting mechanics in rotary needle insertion was investigated along with the exploration of improvements of needle biopsy performance by decreasing the needle cutting and friction forces. The deflections of the needle during insertion were measured to develop a strategy for guiding the needle to the right position in brachytherapy and drug delivery. From an overall perspective, fundamental advances and application problems based on the cutting mechanics of soft tissue for needle were highlighted to lay the foundation for developments of biomedical device and improvements of healthcare procedures.

FInite element study on chip formation and force response in two-dimensional orthogonal cutting of rock

The understanding of the rock-cutter interaction is essential for efficient rock cutting/drilling performed with polycrystalline diamond compact (PDC) cutters in petroleum engineering and gas exploration. Finite element modeling of the rock cutting process still remains a challenge due to the complex material properties of rock, rock fracture and chip formation phenomena and large force oscillations during the dominant brittle cutting mode. A finite element study was conducted to investigate the chip formation and force responses in two-dimensional orthogonal cutting of rock. The Drucker-Prager model that incorporates a simple shear strain failure criterion was exploited to simulate the interactions between the rock and the cutter. A fully instrumented rock cutting testbed was developed to enable the measurements of the three orthogonal force components and of the uni-axial acceleration in the cutting direction along rectilinear tool-paths to evaluate the simulation results. The chip formation phenomena and force response predictions derived by the FEM simulations were in good agreement with the experimental tests.Copyright

Feasibility of Laser Surface Texturing for Friction Reduction in Surgical Blades

Trauma resulting from surgical blade friction can cause several complications and delay the recovery time of a patient. In order to attain optimal tribological properties, an 8 ps pulsed 532 nm Nd:YVO4 laser was used to ablate the cutting edge surface of surgical blades to create micro dimples of ∼110 μm in diameter and ∼30 μm in depth. Additionally, certain arrays of dimples endured an extra laser ablation operation to add a fillet to the dimple rims with the hope of reducing stress concentrations during tissue cutting and reducing friction even further. These surface textures were experimentally investigated through cutting experiments on phantom tissue material. Ultimately, the blades with the cutting surface texture that employed blended dimple rims showed a substantial reduction in friction forces when cutting phantom tissue samples.Copyright

Force Model for Needle-Tissue Interaction

Force modeling of needle insertion into soft tissue is important for accurate needle placement and efficient tissue cutting. In this paper, we studied the pre-puncture and puncture forces during needle insertion. A plane strain FE model was developed to simulate the pre-puncture force prior to tissue rupture. A sensitivity study was performed to investigate the influence of needle and tissue characteristics on pre-puncture force using FE simulation. A force model that incorporates needle geometry and tissue properties was proposed. The force model was able to accurately predict the needle tip force prior to tissue rupture. In addition to studying the pre-puncture force, the puncture force was experimentally characterized for different needle diameters and tip angles. The experimental results show that the puncture force has a strong dependency on needle geometry.Copyright

Comparative Assessment of the Laser Induced Plasma Micro-Machining (LIP-MM) and the Micro-EDM Processes

The paper introduces the LIP-MM process and compares its micro-machining capabilities with micro-EDM in the machining of micro-channels. While, micro-EDM is a well-established micro-manufacturing process and has been at the center of research for the last 15 years, the LIP-MM is a newly developed micro-machining process. Although both processes utilize plasma to perform micro-machining, differences in their plasma generation mechanism and hence differences in their plasma characteristics lead to differences in their micro-machining capabilities. For comparative assessment of their micro-machining capabilities, micro-channels were machined by the two processes at similar pulse energy levels, while other process parameters were maintained at their optimal values, depending on the respective experimental setups used. The comparative assessment was based on the geometric characteristics of the micro-channels, material removal rate (MRR), productivity in the machining of micro-channels, effect of tool wear, and the range of machinable materials for the two processes.Copyright