Journal of Applied Engineering Design and Simulation

A case study on cooling load performance of a large multi-storey house through simulation

2026-06-30T11:33:19+08:00

Air conditioning system consumes the most energy in a residential building; therefore, it is necessary to understand the elements that contribute to its design and operation. One of the important factors is the cooling load of the building, which is the result of multiple heat gains from internal and external sources. The research aims to comprehend the distribution and behaviour of cooling load in a house with the help of a case study. The target building is a simulation model of a three-storey bungalow in tropical climate. DS-HL2 modelling is utilised with building specification and measurement as the input. Simulation finding shows that the rooms located at the rear end of the house experienced peak heat gain as early as 11 a.m., compared to 4 p.m. for the room located in the middle. Also, three passive measures were introduced to the premise. Outperforming roof insulation and overhang shade, tinted glass was observed to be the most effective at 11.4 % cooling load reduction. When the combination of all passive measures was implemented, each room in the house had a unique percentage of cooling load reduction per area. The room with highest benefit was Master Bedroom at 28.1 % cooling load reduction per area.

Simulation-driven evaluation and selection of analog rice extrusion die geometry using design of experiments and finite element analysis

2026-08-22T11:49:32+08:00

Analog rice extrusion dies must resist the applied extrusion load while maintaining low deformation, yet their structural geometry is rarely evaluated systematically before fabrication. This study aims to quantify the effects of edge fillet diameter and die-hole thickness on maximum von Mises stress and total deformation, and to identify the best-performing configuration within a predefined design space. Nine die configurations were generated using a 3² full factorial design with fillet diameters of 1, 2, and 3 mm and hole thicknesses of 10, 12, and 14 mm. Each configuration underwent one deterministic static finite element analysis in Altair SimLab under identical material properties, boundary conditions, mesh settings, and a 7117 N design load. The die material was Aluminum Alloy 6061-T6. Maximum stress ranged from 22.757 to 43.979 MPa, while deformation ranged from 0.008 to 0.016 mm. Across the evaluated levels, increasing both variables reduced the two structural responses, with hole thickness showing the larger main effect. Exploratory main-effects ANOVA and response models supported the observed trends, although inferential results were interpreted cautiously because the simulations were not independently replicated. The 3 mm fillet and 14 mm hole thickness configuration produced the lowest simulated stress and deformation among the nine cases. It is therefore reported as the best-performing tested configuration rather than a globally optimised design. The workflow supports pre-fabrication screening of analog rice extrusion dies and identifies priorities for subsequent experimental and thermo-mechanical validation.

Actuator-level kinematic analysis of a PAM-driven dual four-bar knee exoskeleton for rehabilitation gait assistance

2026-07-14T15:28:25+08:00

Stroke-related gait impairment commonly produces reduced knee coordination and insufficient toe clearance, motivating the development of compliant rehabilitation exoskeletons. Pneumatic artificial muscles (PAMs) offer compliant, biomimetic actuation well suited to rehabilitation gait training; however, existing four-bar linkage exoskeleton studies have focused on mechanism synthesis and joint-level trajectory reproduction without analytically characterising the continuous actuator-level kinematic demands that PAM actuation imposes across the gait cycle. This study develops a closed-loop kinematic framework for a PAM-driven dual four-bar knee exoskeleton, actuated by Festo DMSP-20 fluidic muscles, that maps prescribed rehabilitation knee trajectories to actuator displacement and contraction-rate demands at the preliminary design stage. The mechanism was reconstructed from the KNEXO structural concept using MotionGen simulation and modelled analytically through vector loop-closure analysis and Freudenstein’s equation. A continuous quartic stroke-map formulation was introduced to replace repeated inverse-kinematic computation with a single analytical expression, enabling efficient actuator evaluation throughout the gait cycle. The reconstructed mechanism reproduced the normative knee trajectory with a root-mean-square error of 2.69° over the eight gait-event boundaries, with all gait-event angles remaining within the Perry normative variability band and Freudenstein loop-closure residuals below 5% for both the primary and secondary mechanisms. All PAM contractions remained below 20% of the nominal actuator length, within the 25% practical operating limit of the selected actuator, while the quartic stroke-map reproduced the actuator-contraction relationship with root-mean-square errors of 0.23 cm and 0.37 cm. The proposed framework provides designers with an analytical tool for evaluating actuator contraction displacement, contraction-rate demands, and transmission kinematics in dual four-bar rehabilitation exoskeletons before committing to hardware fabrication.

Influence of aromatic polyamide fibre on the early-age strength development of cold mix asphalt during curing

2026-09-10T12:12:46+08:00

Cold Mix Asphalt (CMA) is widely used for pavement maintenance because of its ease of application, low energy consumption, and ability to be produced at ambient temperatures. However, its relatively slow curing process delays strength development and limits the timely reopening of repaired pavement sections to traffic. This study investigates the influence of Aromatic Polyamide Fibre (APF) on the early-age strength development of CMA during curing. Laboratory evaluations were conducted on unmodified CMA and CMA modified with 0.05% APF using workability, volumetric properties, and Marshall Stability tests after curing periods of 24, 48, 72, and 96 hours. Exploratory linear regression was performed to examine the relationship between curing duration and Marshall Stability. The results show that the APF-modified mixture had a lower measured air-void content (7.08%) than the control mixture (8.42%). The APF-modified mixture exhibited approximately 35% and 18% higher mean Marshall Stability than the control at 24 and 48 hours, respectively, while both mixtures achieved the required Marshall Stability after 72 hours. Exploratory regression indicated an overall curing-time trend but was not statistically significant and therefore interpreted descriptively rather than as a predictive model. Overall, the findings indicate that APF can improve the early-age mechanical performance of CMA, particularly within the first 48 hours of curing, highlighting its potential as a fibre reinforcement for pavement maintenance applications.

Face-centred design approach for modelling and predicting areal surface roughness in freeform surface milling of stavax ESR

2026-09-17T15:42:47+08:00

Freeform surfaces have become a major element in high precision industrial design, such as moulds and dies. These sculptured surfaces are characterised by non-uniform and aesthetic features requiring high-quality surface finishing. Therefore, minimising surface roughness becomes critical, especially when machining Stavax, a well-known material, in moulds and dies. This study aims to optimise 3-axis CNC ball nose milling parameters, namely spindle speed (v_c), feed rate (f_z), and depth of cut (a_p), in minimising areal surface roughness on the B-Spline tensor product of the Stavax freeform profile. A total of 17 experimental runs were designed using a face-centred composite approach (FCD) under the response surface methodology (RSM). Areal surface roughness data were captured via Alicona InfiniteFocus and then evaluated by MountainsLab in compliance with ISO 25178. ANOVA validation indicated a highly reliable predictive model, characterised by an R² of 0.9680, an adjusted R² of 0.9268, and a predicted R² of 0.8762 with the difference less than 0.2. This study also developed the FCD mathematical model for factors influencing the roughness.

One-way fluid-structure interaction analysis of oar blade designs: evaluating hydrodynamic performance and structural flexibility

2026-06-30T11:30:17+08:00

Rowing propulsion relies on complex interactions between the paddle blade and the water, where blade design is crucial in determining efficiency and performance. During the stroke, the oar blade interacts with the water and undergoes structural deformation under hydrodynamic forces. In an actual situation, hydraulic forces and structural responses occur simultaneously, requiring FSI for study and evaluation. Thus, this study aims to evaluate the fluid-structure interaction (FSI) characteristics of three widely used paddle blades, Macon, Big, and Fat blade, using a one-way FSI approach. Computational Fluid Dynamics (CFD) was used to analyse the fluid flow and pressure distribution around the blade, while Finite Element Analysis (FEA) evaluated the structural deformation under hydrodynamic forces. Results revealed the Macon blade produced the lowest propulsive force of 326N at 90º blade position. The Big and Fat blade showed a force increase at 36% and 52%, respectively, compared to the Macon blade. In terms of structure, the Macon blade experienced tip deflection of 46.7mm, and the Big and Fat blade experienced bending with displacements of 11.5mm and 13.6mm, respectively, combined with twisting due to the rotational structure. The flexible blades, such as the Macon, offer smoother transitions and enhanced energy absorption. These findings underscore the importance of balancing blade stiffness, design, and hydrodynamic aspects to enhance rowing performance, offering valuable insights into optimizing paddle blade design

Improving coordinate measuring machine inspection efficiency through inspection-jig redesign: a lean-kaizen action research case study

2026-08-28T11:01:47+08:00

Coordinate Measuring Machines (CMMs) are widely used in precision manufacturing to verify dimensional accuracy and product conformity. Most studies on CMM efficiency focus on measurement strategy, probe-path optimisation, scanning, orientation, or digital inspection planning. Less attention has been given to the effect of fixture batch capacity on repeated loading and unloading. This study examines whether increasing inspection-jig capacity can reduce that handling requirement using a Lean-Kaizen, Plan-Do-Check-Act (PDCA), and action-research approach. The case study was carried out at a precision manufacturing company in Malaysia. Three jig concepts with capacities of 5, 20, and 49 cavities were assessed for capacity, CMM table fit, part location, probe accessibility, loading practicality, and fabrication feasibility. With the sampling requirement fixed at 216 parts per shift, the required loading/unloading cycles fell from 44 with the five-cavity jig to five with the 49-cavity jig, an 88.6% reduction in required handling cycles. Measurement-system adequacy was supported by prior Gage Repeatability and Reproducibility studies on the same CMM, with Total Gage R&R values of 5.97% and 9.56% of tolerance and 23 and 32 distinct categories for two representative characteristics. A targeted positional study was then conducted using the same reference part, removed and reseated at eight representative fixture locations (four corners, centre, and three intermediate positions) over five repeated rounds, giving 40 measurements. All readings were within the 3.310-3.330 mm drawing limits, and a randomized complete block analysis found no statistically significant fixture-position effect at alpha = 0.05 (F(7,28) = 2.177, p = 0.0676). The positional result applies to the eight tested locations and does not establish equivalence across all 49 cavities. Under an illustrative constant-cycle-time assumption of eight minutes per loading/unloading cycle, handling time would change from 352 to 40 minutes per shift. Because actual cycle duration was not measured after the redesign, this scenario does not establish whether handling time scales linearly or non-linearly with fixture density. The study therefore separates the direct cycle reduction from metrological evidence and scenario-based capacity implications.

Simulation and optimisation of silica gel-water adsorption chiller for enhancing the performance of cooling system

2026-07-06T12:02:19+08:00

The adsorption cooling system (ACS) using silica gel-water as working-fluid pair is gaining more traction as a substitute for vapor compression system (VCS) due to its environmental friendliness and low energy cost. This paper focuses on improving the efficiency of cooling processes by utilizing silica gel-water adsorption system. The MATLAB-based simulation models integrated with brute force techniques and empirical lumped analytical simulation were adopted in enhancing the operations. Three operational models (A, B, and C) were utilized, with models A and B validating the experimental setup. Model A simulates a laboratory version of a two-bed chiller which uses the Tóth equation for equilibrium uptake and the Clausius-Clapeyron relations for the pressure dynamics. Model B investigates the performance of a two-bed type adsorption chiller with different adsorbents properties. Both models were aligned with experimental outcomes, with Coefficient of Performance (COP) 0.43 and 0.55, specific cooling capacity (SCC) 74.0 and 69.7 W/kg, specific cooling power (SCP) 19.5 and 10.2 W/kg, across hot water (70 to 80°C) and chilled water (-4 to 20°C). The Mean Absolute Percentage Error (MAPE) was between 2.47 to 4.19%, while the Mean Absolute Error (MAE) was between 0.014 to 0.022. Model C enables predictive analysis via user-defined inputs (adsorbent mass, flow rates and temperatures), employing parallel processing for parametric sweeps and transient phase-switching dynamics. Results highlight the system's adaptability to low-grade heat (70 to 80°C, typical of solar thermal or industrial waste heat) and at subzero temperatures, emphasizing its potential for diverse applications. The computational rigor of the framework is validated through thermodynamic and kinetic accuracy, demonstrating silica gel-water adsorption viability in reducing electricity demand and greenhouse emissions. The findings are beneficial to designers of ACS system using silica gel-water as a working-fluid pair, thus contributing to sustainable solutions, which are aligned with global decarbonization goals.

Numerical evaluation of hydraulic performance of a laboratory-scale Archimedes screw pump

2026-09-28T10:17:51+08:00

Archimedes screw pump (ASP) is a type of positive displacement pump for transporting water from lower to upper incline elevations. It is a simple and robust pump widely used for irrigation, flood mitigation, and in wastewater treatment plants. Although ASPs have been used for centuries, there is a lack of literature related to the optimal hydraulic performance and elucidating the underlying flow mechanisms. This study focuses on numerically evaluating ASP hydraulic performance across various rotational speeds and inclination angles. Experiments have also been performed on a laboratory-scale ASP with three flights, a length of 1500 mm, and an outer diameter of 300 mm for CFD validation. A computational fluid dynamics (CFD) model was developed to replicate the experimental setup, performed using the k-ε turbulence model with sliding mesh and the volume of fluid (VOF) method, which is suitable for liquid flow modeling involving combined free surface flow and rotational motion. The CFD model of ASP was simulated under various rotational speeds (25, 50, 75, and 100 rpm) and inclination angles (20°, 25°, and 30°). The results showed that flow rate and torque increase when rotational speed increases for all inclination angles. A maximum efficiency of 94.4% was obtained at 50 rpm and an inclination angle of 30°. These findings provide a useful reference for identifying optimal hydraulic performance of ASP using a CFD-based framework.

Effect of excitation frequency and pneumatic pressure on the voltage response of a chemically unmodified chicken feather-based contact-separation triboelectric nanogenerator

2026-10-02T11:19:41+08:00

Chemically unmodified waste chicken feathers (CF) offer a potential route for valorising poultry waste as a triboelectric material while avoiding deliberate chemical functionalisation. This study investigates the voltage response of a CF–PTFE contact–separation triboelectric nanogenerator (CS-TENG) under controlled variations in excitation frequency, pneumatic pressure, and CF layer configuration. A full-factorial combination of three excitation frequencies (0.5, 2.7, and 5.0 Hz), three pneumatic pressures (0.2, 0.4, and 0.6 MPa), and three CF configurations (1CF, 3CF, and 5CF) was evaluated, with each condition tested in three separate experimental runs. Within the investigated ranges, the mean peak-to-peak voltage (Vpp) increased consistently with excitation frequency and pneumatic pressure across all CF configurations. The 3CF configuration produced the highest mean Vpp among the tested configurations, reaching 60.33 ± 0.58 V at 5.0 Hz and 0.6 MPa. These findings establish the experimentally observed voltage response of chemically unmodified waste CF in a CS-TENG and demonstrate systematic variations in response with excitation frequency, pneumatic pressure, and CF layer configuration within the investigated ranges. The results are limited to voltage measurements within these parameter ranges; therefore, further current, charge, load-dependent power, and extended-range measurements are required to establish broader energy-harvesting performance.