What is a Sandwich Panel? Structure, Types and Applications

——In-depth analysis of structural design, core materials and multi-field applications

Sandwich panel is a kind of board structure compounded by multi-layer materials, and its core feature is to take the lightweight core layer as the core, and realize the functional composite through the high-strength surface panel and advanced bonding technology. This structural design gives it excellent heat insulation, load-bearing and lightweight performance, which is widely used in refrigerated trucks, construction projects, mobile carriers and other fields.

Sandwich Composite Structure

Sandwich panels utilize a layered composite structure, where each layer of material acts synergistically through a specific process:

1. Exterior skin – fiberglass reinforced plastic (FRP), aluminum alloy, or continuous fiber reinforced thermoplastic (CFRT) to provide a protective layer for aesthetics, strength, and weather resistance.
2. Core material – polyurethane foam (PU), extruded polystyrene (XPS), PET, PVC, polypropylene honeycomb or plywood for lightweight insulation for thermal insulation, vibration damping and structural support.
3. Adhesive layer – water-based environmentally friendly polyurethane adhesive VOC emissions reduced by 98%.
4. Embedded reinforcing materials – embedded materials include wood, aluminum tubes, glass fiber reinforced plastic tubes and high strength plastic rods.
5. Inner skin layer – high tensile strength continuous fiber composite material (e.g. 700 MPa force fiber) to enhance the overall rigidity.

What Types of Sandwich Panels Are Available?

FRP polymer foam sandwich panels

Manufacturing process: Adopting one-piece vacuum composite molding technology to realize seamless bonding of surface material-core material under 10-³Pa vacuum.
Typical data: The thermal insulation efficiency is increased by 47% compared with traditional materials, and the weight of FRP-PET foam sandwich panel with 15mm thickness is only 5kg/m².

Outer layer options

Functional characteristics: bear the main mechanical loads, corrosion and abrasion resistant

• FRP (Fiberglass Reinforced Plastic): impact resistant, corrosion proof and suitable for wet or rainy environments.
• CFRT (Continuous Fiber Reinforced Plastic): a cost-effective alternative to FRP, eco-friendly and recyclable, with excellent resilience and easy repair.
• Pre-painted galvanized steel: weather resistant, versatile and low maintenance.
• Aluminum skin (0.5-2mm thickness): lightweight, corrosion-resistant and thermally conductive, up to 60% lighter than steel.
• Stainless steel: heavy duty durable material for high temperature or corrosive environments.
• PP non-slip surface: non-slip flooring for wet or industrial environments.

Core options

Core value: Realization of thermal insulation, vibration damping and structural reinforcement

• PP Honeycomb Core: Polypropylene construction with shock absorbing and rigid properties.
• XPS foam: closed cell insulation for insulation applications such as refrigerated trucks.
• PU foam: Adjustable density with excellent acoustic and vibration damping properties.
• PET foam: environmentally friendly, recyclable and highly rigid.
• PVC foam: lightweight and easy to mold, suitable for customized designs.

Core Material Type	Thermal Conductivity (W/m·K)	Compressive Strength	Representative Applications
PU Polyurethane Foam	0.023	200-400 kPa	Refrigerated Truck Bodies
XPS Extruded Polystyrene	0.027	400 kPa	Freight Box Trucks
PET Foam Material	0.033	Above 500 kPa	High-end RV Flooring
Polypropylene Honeycomb	—	Lateral Compressive Strength 1.5 MPa	Box Trucks, Camping Trailers

Adhesive layer

Sandwich panel adhesive layers are used to bond panels and core materials to enhance the sealing, stability and peeling resistance of sandwich panels. Common adhesives include:

1. Polyurethane adhesives
2. Epoxy adhesives
3. Acrylate adhesives

Honeycomb sandwich panels

Structural features: Hexagonal/circular honeycomb structure makes the panel with anisotropic mechanical characteristics, reducing weight by 30% while maintaining high compressive strength, mainly used in box trucks side panels, front panels, floors, door panels, roof panels, and other scenarios with high requirements for lightweighting.

Wood composite sandwich panels

FRP surface layer is composite with plywood core, combining the economy of organic materials and the recyclability of thermoplastic materials, using thermo compression molding process, adapting to the needs of complex curved surface design. Its fire resistance is certified by EN13501-1 fire protection class B1.

Metal composite sandwich panels

Process cost: 25% lower than traditional welded structure
Bending test: 3mm aluminum plate + PU core material combination load up to 150kg/m².

Type	Core Material	Application Scenarios	Performance Advantages
Polymer Foam Sandwich Panel	PU, XPS, PET Foam Materials	Refrigerated Truck Bodies, Cold Storage Doors	Low thermal conductivity down to 0.023 W/(m·K), withstands temperatures as low as -40°C
Honeycomb Sandwich Panel	Polypropylene (PP) Honeycomb Structure	Box Truck Roofs, Engineering Vehicle Toolboxes	Weight reduced by 40%, impact resistance improved by 15%[^5]
Composite Sandwich Panel	Plywood + Continuous Fiber Reinforced Layer	Modular Building Walls, Ship Interiors	Combines the cost-effectiveness of wood with the weather resistance of composite materials
Metal Sandwich Panel	Aluminum-Plastic Composite Core Material	Container House Exterior Walls, Industrial Factory Roofs	Fire rating up to A2, service life exceeding 20 years

Why Choose Sandwich Panels?

1. Excellent thermal insulation: low thermal conductivity reduces energy costs in refrigerated trucks or thermostatic buildings.
2. High strength-to-weight ratio: outperforms traditional materials while being 70% lighter than steel or concrete.
3. Rapid installation: Modular design simplifies assembly and reduces project time by up to 50%.
4. Cost Effectiveness: Mass production reduces waste and its long life reduces replacement costs.
5. Fire performance: Certain core materials (such as mineral wool) meet stringent fire safety standards.

Cross-Industry Applications of Sandwich Panels

Transportation

• Refrigerated truck and trailer box:

The sandwich panel with XPS/PU core material can keep the constant temperature of perishable goods.

The sandwich panel with PU/XPS foam core material has a temperature rise of only 1.2℃ in the compartment after 72 hours of simulation test in -40℃ environment.

The number of structural parts is reduced by 35% by using 700MPa continuous fiber reinforced skin of a brand model.

• Manufacture of new energy carriers:

Lightweight benefits: Pure electric box trucks use sandwich panel box to increase range by 23%.

• Tool box body:

Composite sandwich panels for categorized tool storage and shock protection

• RV and Camper Bodies.

Lightweight and durable for mobile living spaces.

• Dry van trucks

Fiberglass XPS foam sandwich panels, fiberglass honeycomb sandwich panels for significant weight reduction and impact resistance.

Building structures

• Modular Housing:

Prefabricated walls and roofs allow for the rapid construction of offices, hospitals and schools. Sandwich panels are used as wall and flooring materials for modular buildings, shortening the construction cycle by more than 50%.

Construction efficiency: A mobile square hospital built with sandwich panels can be erected in 12 hours with 200 m² units.

Energy saving data: 61% improvement in energy saving efficiency compared to brick-concrete buildings.

• Exterior walls and roofs

Water-resistant skin with insulating function for energy-saving design.

• Cold storage partitions

XPS core sandwich panels meet the strength and sealing requirements of long-term low-temperature environments.

Cold storage and special purpose

• Walk-in freezers:

Sandwich panels with a thickness of 30 mm or more prevent thermal bridging effects in industrial refrigeration.

• Cleanrooms and laboratories:

Smooth, non-porous surfaces meet hygiene and contamination control standards.

Marine Industry

The superstructure of a certain type of yacht uses PVC sandwich panels, reducing the structural weight by 28%.

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Frequently Asked Questions (FAQ)