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

2026-08-24T16:56:48+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.