Damage and failure evaluation of diamond wire for multi-wire sawing of hard stone blocks through modelling and numerical simulation
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-01-01 |
| Journal | MATEC Web of Conferences |
| Authors | Daniel Gomes, Andreia AraĂşjo, R. MarquĂŞs, JosĂŠ PatrĂcio, VĂtor Lopez |
| Institutions | Universidade do Porto, Institute of Mechanical Engineering and Industrial Mangement |
| Citations | 2 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study presents a validated Finite Element (FE) model of a diamond wire, developed using Abaqus⢠software, aimed at evaluating damage and failure mechanisms under multi-wire stone sawing conditions.
- Core Achievement: A detailed 3D numerical model of a 7x7 right regular lay steel wire rope, Thermoplastic Polyurethane (TPU) coating, and diamond beads was created and subjected to complex mechanical solicitations (tension, pre-torsion, and bending).
- Validation Success: The diamond wire numerical model achieved strong correlation with experimental tensile tests, demonstrating an error smaller than 6%.
- Modeling Innovation: To accurately represent the mechanical behavior of the wire rope, a specified distance âtie constraintâ was implemented between strands to simulate the tightening effects induced during manufacturing tension.
- Critical Stress Findings: The superposition of tension and bending stress resulted in a maximum von Mises equivalent stress of 1200 MPa on the top wires of the wire rope, indicating the primary failure location.
- Design Optimization Insight: The pre-torsion applied during manufacturing significantly affects load distribution. Reducing the standard pre-torsion (1.5 turns/m) by 33% (to 1 turn/m) resulted in a 16% reduction in torsion torque and achieved a more homogenous stress distribution across the core and outer strands.
- TPU Coating Analysis: The model successfully identified stress concentration points on the TPU coating, specifically at the extremes and the first fillet of the bead thread, which are known areas for premature failure.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Wire Rope Construction | 7x7 | N/A | Right regular lay |
| Wire Rope Overall Radius | 1.575 | mm | Geometric dimension |
| Outer Strand Pitch Length | 21.5 | mm | Lay length |
| Wire Rope Material (Steel) E | 180,000 | MPa | Youngâs Modulus (FE input) |
| Wire Rope Material Rp0.2 | 2160 | MPa | Yield Stress (Perfectly plastic assumption) |
| Coating Material | TPU | N/A | Thermoplastic Polyurethane (Hyperelastic) |
| Coating Outer Diameter (OD) | 4.4 | mm | Polymer coating dimension |
| Coating Inner Diameter (ID) | 2.16 | mm | Polymer coating dimension |
| Model Length | 27 | mm | Representative length (pitch between consecutive beads) |
| Max Applied Tension (Cutting) | 2000 | N | Multi-wire sawing load case |
| Standard Applied Torsion | 1.5 | turns/m | Production pre-torsion (9.42 rad/m angular deformation) |
| Smallest Pulley Diameter | 780 | mm | Source of highest bending stress (Hedel machine) |
| Max Von Mises Stress (Wire Rope) | 1200 | MPa | Top wires under combined tension and bending |
| Torsion Torque (Standard 1.5 turns/m) | 861 | Nmm | Predicted torque value |
| Numerical Model Validation Error | < 6 | % | Relative to experimental tensile test |
Key Methodologies
Section titled âKey Methodologiesâ- 3D Geometry Creation (Soliworksâ˘): The 7x7 wire rope geometry (49 individual wires) was defined using extrude sweep along helix paths. Single helix paths were used for the core strand wires, and double helix paths were used for the outer strand wires.
- Wire Rope Length Definition: The model length was set to 27 mm, corresponding to the pitch between consecutive diamond beads, which is longer than typical literature models (3-9% of outer strand pitch) to ensure representative bead interaction.
- Wire Rope Contact Simulation (Abaqusâ˘): A critical âtie constraintâ was applied between the outer wires of the core strand and the outer wires of the outer strands. This constraint was distance-specified to simulate the elimination of gaps due to manufacturing tension, ensuring the model stiffness matched analytical results (Costello model).
- Coating Material Characterization: The TPU coating was characterized experimentally (tensile and compression tests). The hyperelastic behavior was modeled in Abaqus⢠using the Van der Waals model, selected for its balance of accuracy and computational efficiency.
- Diamond Wire Assembly: The TPU coating was modeled as a hollow circular profile extruded along the wire rope axis. Negative geometry functions were used to embed the wire rope inside the coating and to define the diamond bead geometry on the coating exterior.
- Load Case Application (3 Consecutive Steps): The complex mechanical solicitations were applied sequentially to a reference point at the edges of the model, while the diamond bead was constrained:
- Step 1 (Tension): 2000 N point load applied in the traction direction.
- Step 2 (Torsion): Angular displacement of 0.1272 radians applied around the axis (simulating 1.5 turns/m pre-torsion).
- Step 3 (Bending): Displacement of 0.23 mm applied orthogonally to the axis, simulating the bending stress induced by the 780 mm pulley.
Commercial Applications
Section titled âCommercial ApplicationsâThe developed numerical model and resulting analysis are directly applicable to the manufacturing and operational optimization of diamond wires used in the stone processing industry.
- Quarrying and Stone Processing: Used for the extraction of large stone blocks and the shaping of ornamental stones in block processing plants.
- Tool Design and Manufacturing: The model allows manufacturers (like Diamond Service Portuguesa, Lda) to vary geometrical and material characteristics (e.g., wire rope lay, coating material, pre-torsion level) to evaluate their influence on stress distribution.
- Service Life Improvement: By identifying high-stress zones (e.g., top wires, bead fillets), the model supports the implementation of design changes to enhance durability, damage resistance, and achieve longer service life for diamond wires.
- Multi-Wire Sawing Machine Optimization: Provides data to correlate production parameters (pre-torsion) with operational performance (bead rotation and wear), supporting the optimization of machine settings (e.g., down feed speed, tension).
View Original Abstract
Diamond wires are high-speed, efficient and cost-effective stone cutting tools used both in quarries, to obtain large stone blocks, and in block-processing plants, to shape ornamental stones. Diamond wires are generally composed by a wire rope with evenly spaced diamond beads fixed by a polymer or rubber coating. A numerical model of the diamond wire was developed in Abaqus⢠software aiming to study the damage and failure of the steel wire during the cutting process. The model is intended to support the development of this component with enhanced durability and damage resistance. Previously in this work, a detailed three-dimensional (3D) and numerical model of a 7x7 wire rope was created, followed by experimental validation. The diamond wire model was then based on the wire rope model, with the addition of the polymer coating and the diamond beads. The developed diamond wire model presents an error smaller than 6% relative to the experimental tensile test, corresponding to a valid representation of the component. This model has practical significance for the mechanical evaluation of the diamond wire, supporting further developments, with special focus on its design and manufacturing, to achieve longer service life.