Design for Additive Manufacturing Inspired by TRIZ

With the rise in popularity of additive manufacturing (AM), relevant design methodologies have become necessary for designers to reap the full benefits from this technology. TRIZ is a problem-solving tool developed to assist with innovative and creative solutions. This paper aims to create a new TRIZ matrix specifically developed for designers using additive manufacturing. The TRIZ matrix offers designers general innovative design solutions to improve specific features of a design while not sacrificing the effectiveness of other features. The proposed matrix can help effective design decision making for additive manufacturing in an early design process as well as a redesign process. Also, a design for additive manufacturing (DfAM) worksheet is provided to enable users to easily find specific design solutions for certain additive manufacturing techniques based on the general solutions derived by the TRIZ matrix. To illustrate the potential of this AM specific TRIZ matrix, case studies are presented.

Past Infrastructures and Future Machine Intelligence (MI) for Biofuel Production: A Review and MI-Based Framework

Recent interest in alternative energy sources, particularly biofuels from biomass, is becoming increasingly evident due to energy security and environmental sustainability concerns, such as depletion of conventional energy reserves and carbon footprint effects, respectively. Existing fuels (e.g., biodiesel and ethanol) are neither sustainable nor cost-competitive. There is a need to integrate the recent advanced manufacturing approaches and machine intelligence (MI) techniques (e.g., machine learning and artificial intelligence), targeted on the midstream segment (i.e., pre-/post-conversion processes) of biomass-to-biofuel supply chains (B2BSC). Thus, a comparative review of the existing MI approaches developed in prior studies is performed herein. This review article, additionally, proposes an MI-based framework to enhance productivity and profitability of existing biofuel production processes through intelligent monitoring and control, optimization, and data-driven decision support tools. It is further concluded that a modernized conversion process utilizing MI techniques is essential to seamlessly capture process-level intricacies and enhance techno-economic resilience and socio-ecological integrity of B2BSC.

Mechanical Design for Accuracy of Linkage Servo Press for Near-Net Shape Forming

The accuracy of machine is important to achieving highly accurate shapes. This paper is focused on mechanical design of highly accurate mechanical linkage servo press applicable to (near-)net shape forming. The effects of geometric errors, deformations under heavy loads and ram tilting are analyzed. A top-down design for accuracy approach is proposed: First, accuracy model for identification of inaccuracy-causing factors and their interlinking relations is developed. Then, based on this model, top accuracy index are decomposed and translated into structure design specifications at component level. Both analytic and simulation methods are employed for design for accuracy in aspects of dimensional and geometric tolerance allocation, stiffness synthesis and anti-eccentric load capability. A case study of mechanical design for accuracy of a six-linkage mechanical servo press is also presented to demonstrate and test the proposed design approaches.

Nonlinear Design Model for Multi-Threshold Accelerometer Utilizing Magnetic Induced Multistable Mechanisms

Different from traditional accelerometer, multi-threshold acceleration switch can be triggered to different working states by external accelerations without complex auxiliary circuits and controlling elements, which has great application potentials in aerospace, vehicle safety and consumer electronics. In this paper, a novel multi-threshold acceleration switch with anti-overloading function is designed and fabricated by incorporating both magnetic multi-stable structures and compliant cantilever contacts, which also can be used to distinguish specific acceleration pulse. To enhance the contact reliability, the magnetic compliant locking mechanism is introduced to prevent bouncing back phenomenon under overload acceleration. Considering the air-damping and multi-magnetic fields coupling effect, the dynamic design model is proposed for analyzing the nonlinear switch response. Then, threshold accelerations can be determined as ac1 = 3.78g, ac2 = 10.2g and ac3 = 6.95g in one direction while threshold accelerations in opposite direction are ac4 = 4.9g, ac5 = 8.47g and ac6 = 5.6g. The switch shows excellent threshold acceleration detection capability, and the inertial switch keeps open while the external acceleration is 0.2g less than the predefined threshold value. The experimental results show that the threshold acceleration with specific pulse width can be accurately identified, and the switch can bear strong overload acceleration comparing to traditional switches. Consequently, the proposed design method provides a new way for intelligent mechanical inertial sensors.

An Attempt of Error Tracing and Compensation Method of the Linkage Error of Five-Axis CNC Machine Tool

Nowadays the five-axis machine tool is one of the most important foundations of manufacturing industry. To guarantee the accuracy of the complex surface machining, multi-axis linkage performance detection and compensation of five-axis machine tools is necessary. RTCP (Rotation Tool Center Point) is one of the basic essential functions for the five-axis machine tools, which can keep the tool center with the machining trajectory when five axes move synchronously. On the basis of RTCP function, a way to detect multi-axes linkage performance of five-axis machine tools is briefly introduced, and linkage error model is built in accordance with the topological structure of machine tool. Based on the feature of the linkage errors of the five-axis machine tool, the error tracing and compensation method is proposed. Some simulations and experiments that verify the error tracing method could locate the linkage error category are established. Therefore, a new attempt to detect and compensate the linkage error of the five-axis machine tool is provided in this paper.

Torsional Tip Motion of Double Beam Atomic Force Microscopy

This paper investigates the vibration of a coupled microcantilever beam structure, in which a rigid body at their free end connects the two beams. The coupled beams are under equal and out-of-phase forces applied by piezoelectric films, which result in overall torsional motion. The equations describing the motion of the structure as well as the boundary conditions are developed using the Hamilton principle under the assumption of the structure being an Euler-Bernoulli beam. Two equations for each beam are realized: bending and torsional equations, which are combined in one torsional equation. The equation is solved using Galerkin approximation. The effects of dimensional parameters and input parameters are investigated including height, width, thickness, beam arrangement, applied voltage, input frequency, and mass of the tip. Geometry and mass were found to have significant effects on the angle, while input voltage was found to have a small linear effect. The overall sweeping motion was found to have an angle well below one degree in general. This shows that while the piezoelectric actuators can generate torsional sweeping, the effect is at a small angle that depends more on design than actuation force.

Characterization of a Non-Interdigitated Comb Drive

This paper reports on the design, fabrication, and characterization of non-interdigitated comb drive actuators in Silicon-on-Insulator (SOI) wafers, using a single mask surface microma-chining process. The response of the actuator is analyzed numerically and experimentally. The results show at the fundamental frequency; it behaves as a longitudinal comb drive actuator. At a higher frequency, it exhibits a high-quality factor which is appropriate for sensor applications.

Identifying Design Interventions in Cities for Urban Sustainability

Cities have been the focus of recent sustainability and climate change mitigation efforts primarily because of unprecedented urban growth and ever-increasing resources consumption. A worrying trend has been the ever-decreasing life of buildings in cities because of premature building obsolescence. Premature building obsolescence has been cited as the major driver of demolition waste which accounts for more than 40% of total waste generated annually. This waste stream poses a bigger challenge as the pressure on natural resources increases with urban growth. A traditional way of looking at the urban sustainability has been from the perspective of the environmental sciences and waste management methods. Analyzing urban areas with design science perspectives could provide novel insights to improve existing resource consumption patterns and transform sustainability growth in cities. This study focuses on the problem of demolition waste arising from the premature building obsolescence in cities. It applies a design research methodology framework for identifying existing problems associated with demolition waste and generating strategies to transform cities into more sustainable urban systems. In the problem clarification phase, a detailed literature review was supported with stakeholder’s interviews to identify the state-of-art for building demolition process and demolition waste. Research was further extended to descriptive study-I phase to carry out a demolition case study and generate support tools to enable transformation in the existing scenario for achieving a desired state. Singapore, a dense city state of South-East Asia has been taken as a case study in this research. Results show that applying design research methods could help open-up a new dimension to solve urban sustainability challenge for built environment. It highlights that material reuse could lead to significant improvement in the built environment sustainability but the challenge associated with realization of material reuse practice needs to be addressed. Descriptive study-I concludes with the strategies on creating a reuse market through entrepreneurial innovation and an alternative material supply chain of secondary materials for regional housing demand. These results highlight the role of design research methods for tackling complex systems level problems in cities.

TRIZ Application in Bionic Modeling for Lightweight Design of Machine Tool Column

The selection of biomimetic prototypes mostly depends on the subjective observation of a designer. This research uses TRIZ to explore some inferential steps in bionic design of the heavy machine tool column. Conflict resolution theory of TRIZ is applied to describe improved and deteriorated parameters and a contradiction matrix is used to obtain recommended inventive principles. A reference table of solutions corresponding to the biological phenomenon and TRIZ solutions is formed to expedite retrieving the biomimetic object. Based on the table, herbaceous hollow stem is selected to imitate column structure. Four kinds of plant are chosen from the biological database. To select the best from four candidates, a bionic ideality evaluation index is proposed based on similarity analysis and ideality evaluation theory in TRIZ. Thus, the bionic effect can be described and compared quantitatively. Bionic configuration is then evolved concerning manufacturing requirements. Size optimization of stiffener thicknesses is implemented finally, and satisfactory results of the lightweight effect is obtained.

Hysteresis Identification of Carbon Nanotube Composite Beams

Nanocomposites made of a hosting polymer matrix integrated with carbon nanotubes as nanofillers exhibit an inherent hysteretic behavior arising from the CNT/matrix frictional sliding. Such stick-slip mechanism is responsible for the high damping capacity of CNT nanocomposites. A full 3D nonlinear constitutive model, framed in the context of the Eshelby-Mori-Tanaka theory, reduced to a 1D phenomenological model is shown to describe accurately the CNT/polymer stick-slip hysteresis. The nonlinear hysteretic response of CNT nanocomposite beams is experimentally characterized via displacement-driven tests in bending mode. The force-displacement cycles are identified via the phenomenological model featuring five independent constitutive parameters. A preliminary parametric study highlights the importance of some key parameters in determining the shape of the hysteresis loops. The parameter identification is performed via one of the variants of a genetic-type differential evolution algorithm. The nanocomposites hysteresis loops are identified with reasonably low mean square errors. Such outcome confirms that the 1D phenomenological model may serve as an effective tool to describe and predict the nanocomposite nonlinear hysteretic behavior towards unprecedented material optimization and design.